Issue 112 June 2014 - nutwooduk.co.uk

ISSN 1748-9253

Know your StandardsBy John WoodgateSee page 16

EMCUK 2014 7th & 8th Octoberwww.emcuk.co.ukSee pages 6-8 for details

the journal Issue 112 June 2014

The EMC Journal June 2014 2

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The EMC Journal June 20143

What’s In This Issue

www.theemcjournal.com www.emcgoggles.com www.emcuk.co.uk www.emcacademy.orgEvery effort has been made to ensure that the information given in this journal is accurate, but no legal responsibility is accepted for any errors, omissions or misleading statements in that information cause by negligence or otherwise, and no responsibility is accepted in regard to the standing of any firms, companies or individuals mentioned or for any advice given by them.

News

EMCUK 2014 Workshop programme

Banana Skins

John Woodgate’s Column

Know Your Standards

Product Gallery

EM Simulation of Automotive Radar Mounted in Vehicle Bumper By Remcom – Electromagnetic Simulation Solutions

Using close-field probes to reduce design risks early in a project By Keith Armstrong, Cherry Clough Consultants

Advertisers Index

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Editorial

Do you have an article to contribute?This is now my third issue of the EMC Journal, issue 112 overall. Thanks to all those who have offered their continued support for EMC Goggles Ltd taking on this publication. Thanks also to all those who sent me messages of support for playing in the pool competition earlier this year. And, thanks again to the support of Microlease and Agilent Technologies for their sponsorship of the Wales pool team also.

Well, in recent weeks we’ve received the news that the Multimedia Immunity standard, EN 55035, was not ratified by Cenelec BT. I feel that is a shame because I have been heavily involved in the creation of the CISPR drafting of this standard over many years. For me, it’s a clearer standard and I believe it is a good standard for all those multifunctional IT-style products. Perhaps the situation will change and it gets another consideration. I believe there is something of an unsettled situation within

the EMC side of the EC and Cenelec at the moment, so let’s see what develops.

For my colleague, Jim Wood, retiring Chairman of the EMCTLA, and Chris Coleman, retiring Working Group C Chairman at the EMCTLA, I would like to wish you both all the best and I hope we continue to meet up on a regular basis.

Finally, I just want to put a call out to those engineers or managers who may want to contribute technical articles to this Journal. Do email me on [email protected] any articles of interest that you may have and I shall consider them for publication.

John DaviesEditor, The EMC Journal

39

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News

Front Cover

Hero image, AR, page 9Circle top, Voltronics, page 18Circle middle, REO, page 20Circle bottom, Rohde & Schwarz page 21

The EMC JournalFree to readers worldwide June 2014 – Issue No. 112

Published every other month First Issue March 1995

Editorial & Publishing Director:John Davies

[email protected]

EMC Goggles Ltd26 Rumney Walk

LlanyrafonCwmbranNP44 8RN

www.theemcjournal.com

www.compliance-club.com

EMC Goggles Ltd provides classroom and laboratory training as well as product and compliance consultancy to companies worldwide. Director, John Davies, has been involved in EMC since 1990 and is a UKAS technical assessor, a member of British

Standards EMC committees and appointed UK expert to the IEC/CISPR. John is also Secretary of the EMC Test Labs Association.

EMC Test Labs Association Chairman retiresJim Wood, Chairman of the EMCTLA, has retired. At an EMCTLA meeting in May 2014, Jim was present and he was awarded Lifetime Honorary Membership of the EMCTLA and presented with an inscribed barometer. Jim has been actively involved in the EMCTLA for pretty much all of its 22 years of existence.

Jim gave a speech where he talked of his passion for the work and activities of the EMCTLA. He also made a call to the members to bring along their young engineers to the meetings to assure a successful future for the trade association. Jim received a rapturous applause for his speech and we all wish him well for the future.

Photo: EMCTLA Secretary John Davies and retiring EMCTLA Chairman Jim Wood.

Rohde & Schwarz joins M2M AllianceRohde & Schwarz is strengthening its commitment to machine-to-machine (M2M) communications and the Internet of Things (IoT) by joining the M2M Alliance.

On April 1, 2014, Rohde & Schwarz joined the M2M Alliance, the largest association for the machine-to-machine sector. Jörg Köpp, who is responsible for the M2M/NFC market segment at Rohde & Schwarz, says, “The advanced networking between people and machines and among machines themselves is completely changing our lives. It is opening up entirely new fields of application for our wireless test solutions. With our commitment to the M2M Alliance, we want to promote this future oriented technology worldwide.”

Eric Schneider, first chairman of the M2M

Alliance, says, “We are very pleased to welcome Rohde & Schwarz to the M2M Alliance and gain a wireless specialist that has stood for quality and innovation in wireless communications technology for 80 years. The company’s wireless test solution expertise and comprehensive portfolio make it an asset to the entire M2M industry.”

The reliability and security of mobile and wireless technologies are crucial to the success and acceptance of M2M applications. There are many industries where wireless applications have not previously played a role, but now even household appliance manufacturers, for example, are facing the challenge of integrating wireless components into their products. They need to verify that

these components function correctly and obtain any necessary certification.

Rohde & Schwarz supports these users by providing T&M equipment for almost all mobile, wireless and positioning technologies, from LTE/LTE-Advanced, UMTS/HSPA(+), CDMA2000®, Bluetooth® and WLAN wireless Internet access to GPS/Galileo. Rohde & Schwarz also offers specific test solutions for eCall and vehicle to vehicle communications. Solutions for secure M2M communications and monitoring of associated networks round out the portfolio.

For more information: http://www.rohde-schwarz.com/ad/press/m2m http://www.m2m-alliance.com Christian Mokry – T: 0049-89-4129-13052


NewsTelonic Instruments sponsors local Reading Rugby Club youth team

Telonic Instruments are sponsoring a youth team which is part of the local Reading Rugby Club and is designated CODE (Centre of developing excellence) for youths of 17/19 with the idea that they progress to more senior teams.

Reading Rugby Club was formed way back in 1898 when three senior officials from the RFU met in Pangbourne. From this inauspicious start the Berkshire Wanderers was formed. The club continued to thrive and shortly before the Second World War some land at Holme Park, Sonning, was purchased and pitches were laid out. After the War, a new club and stand was erected. In 1956 the club changed its name to the Reading Rugby Club, in order to keep the town name after the founding of another local club which subsequently became the Abbey Rugby Club.Reading Rugby Club continues to expand and now includes two ladies’ teams. In 2013 it was decided to form another team to find and train male players between 17 and 19 for the first XV. This is part of the club’s structured progression.

Doug Lovell Telonic’s Sales and Marketing Director comments “A member of our long standing staff is a player who has migrated successfully to the senior team from CODE. Our policy is to support young people who are interested in sport. We can do

this by supplying the full clothing kit and will continue to support them for the foreseeable future.”

For further information contact: Doug Lovell at [email protected] or T: 0118 9786911

EMC UK 2014 Exhibition & Workshops

The preparations for EMC UK at Newbury Race Course on 7th & 8th October are well under way, with 36 stands already booked and the outline workshop program being put together as this issue goes to print.

The workshop outline program is as follows, for which we would like to put out a call for papers, for all the sessions other than those presented by our regular training provider Keith Armstrong.

We have extended the call for papers for the workshop program until the end of June 2014, should you wish to submit a paper then please send a short synopsis to Alan Warner at:

[email protected]

The New Product Innovation session is primarily open to the exhibitors, with the emphasis on Innovation.

Should you be interested in exhibiting please contact Alan Warner or for further information go to www.emcuk.co.uk.

To register for the workshops, again go to www.emcuk.co.uk although you will be directed to register for either the training workshops or the technical workshops, delegates are free to attend any of the individual sessions they wish.


Training Workshop Technical Workshop

AM EMC Fundamentals Theory & Practice Chairman Nick Wainwright York EMC Services

Power Drives & ConvertorsChairman Tim Williams Elmac Services

Scope:- Medium and high power switchmode converters are becoming ever more common, but their cost in EMC terms is high – harmonics of the switching frequency cause both external and intra-system interference to many types of victim. This session will look at the fundamental mechanisms that couple interference out of the converter and will then consider the various mitigation measures that need to be employed. Interested parties will be involved with the electric vehicle, renewable energy, industrial and white goods sectors amongst others.

PM Cost-effective PCB Design & Layout for EMC,SI and PI Presented by Keith Armstrong Cherry Clough Consulting Ltd

The good EMC engineering techniques that are now essential for almost all PCBs for the most cost-effective EMC compliance, plus the most cost-effective signal integrity (SI) and power (PI), to help get to market quicker with products that cost less to manufacture.

Topics include: Segregation; Interface Suppression; Ground and Power Planes; Power Supply Decoupling, and Layer Stack-Ups.

Electromagnetic EnvironmentChairman Ian MacDiarmid Scope:- This session will invite papers on a wide range of subjects around the electromagnetic environment. It is common to think of radio transmitters in close proximity to electronic systems forming the electromagnetic environment and with the growth in the use of radio communications (fixed and mobile), this problem continues to grow. However, it should be recognised that nature in the form of Lightning creates a very significant environment, not just to the systems that it strikes or is near but the case of Lightning attaching to power lines and the ground in proximity to underground cables forms a significant induced pulsed threat to any connected system within a few kilometres.Nature can also create significant threats to wide-spread systems as a result of Solar activity and its effect on the Geo-magnetic system surrounding the Earth. A man-made exploitation of this arises from exo-atmospheric nuclear explosions. These should be taken into account in the design of critical, widely distributed electrical infrastructure. Product designers continue to create products with a mixture of highly emissive and highly sensitive electronics. For example, energetic motor drive systems combine with control electronics, extremely high power fast operating switching devices (e.g. Gallium Nitride) embedded in electronics. Such combinations continue to challenge EMC designers.Papers are invited on topics which explore any issue associated with a general view of the Electromagnetic Environment, either as design, analytical or test and qualification challenges.

Tuesday 7th October 2014


Training Workshop Technical Workshop

AM Believing in Test Reports Chairman John Davies

Scope:- For manufacturing or design engineers, often the end of their involvement is EMC on a product is when they get the test report. So what help is there for those who start with a test report. These would be retailers, on-sellers, importers, distributors, etc. Such people often start their EMC involvement with a product in one hand and a test report in the other. How can they draw confidence from the EMC test report to believe in the compliance of the product? This session investigates.”

New Product InnovationsChairman Paul Duxbury

Scope:- With the emphasis on innovation this session is primarily aimed at our exhibitors and associated research organisation to provide delegates with the up to date ideas within industry.

PM PCB design & Layout for BGAs & Gb/s serial comms, for cost effective EMCPresented by Keith Armstrong Developing the good EMC engineering techniques from the first workshop to address the special PCB problems for SI, PI and EMC associated with BGAs and other small-form-factor packaged ICs, and serial digital communications at rates of above 1Gb/s.

EMC SimulationChairman Alistair Duffy

Scope:- “Simulation in EMC can be a helpful diagnostic tool, an investigation tool and can help to visualise fields in a way that is not possible experimentally. Papers are invited on all aspects of simulation for EMC but especially on using simulation alongside ‘physical’ systems.

Wednesday 8th October 2014

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Banana Skins...Editor’s note: I receive many potential Banana Skins, and no doubt they are just the tip of the EMI iceberg. Keep them coming – but please don’t be disappointed if your contribution doesn’t appear for a while, or at all.

830 Always ask, even if the answer seems obvious

Pat André of André Consulting, Inc. shared a story that reminds us that it is good practice to ask more questions, even if the answers seem obvious, to get the needed solution. As usual, the story is told from Mr. André’s perspective.

“While consulting for a client, I was approached by a different company who was performing lightning testing at the same laboratory as my client’s. This company was having a great deal of difficulty passing a lightning test. When I saw the unit and the test they were trying to pass, my first question was, “Can you shield these cables?” I was told no.

The unit was small, and although the test levels were not very high, the size of the transient suppression required to pass this test would not have fit inside the box. So we tried several other filtering techniques, with very little success. Therefore, in desperation, I questioned the client more about the shielding issue, with the thought of approaching their customer and requesting if we could shield the signal cables in question.

They told me it was not the customer who said they could not shield the cables, but another consultant – who was worried about “ground loops” (What?). Once I was clear on this, we went to their engineering laboratory, grabbed some overbraid, and shielded the signal lines, assuring both ends of the shield were well bonded to the connectors.

Back at the testing laboratory, the test engineer and the head engineer from my client’s company were both weary after many failures. So, starting at a low level, 100 amperes injected current, they slowly worked their way up to the test limit of 150 amperes. After passing at 140 amperes, the test engineer said, “Okay, are you ready for 150 amperes, the full test level?” We all assured him that we were ready. When the test engineer initiated the test, we immediately heard a large BANG! We watched in stunned disbelief as sparks flew and smoke escaped from each connector.

My client looked like he was ready to change careers, hanging his head in defeat. At that point, the test engineer turned to me and apologetically said, “Oops. That was 1,550 amperes.”

Now that I knew the reason for the sparks and smoke, I turned to the customer engineer and said, “Wait, this may be okay. Check the unit. Is it still working?” After a moment, he said, “Yep. It’s working fine!”

I told the customer engineer that I could get off his payroll at that point, since his unit appeared to pass at 10 times the test level. But, he would have none of that. He told me that I was to sit there and watch the rest of the four hours of testing. The rest of the morning was quiet, and I almost felt guilty for invoicing them for that time.

Almost. I was just glad I pursued the shielding question.”

(Taken from ‘Chapter Chatter’ in the 2012 IEEE EMC Magazine Vol 1 Q3, available from http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=06347045)

831 Explodingharmonicfiltercapacitor causes Queen Mary 2 to drift for 1 hour

SYNOPSIS

At 0425 on 23 September 2010, as RMS Queen Mary 2 (QM2) was approaching Barcelona, an explosion occurred in the vessel’s aft main switchboard room. Within a few seconds, all four propulsion motors shut down, and the vessel blacked out shortly afterwards. Fortunately, the vessel was clear of navigational hazards and drifted in open sea.

T h e e m e rg e n c y g e n e r a t o r s t a r t e d automatically and provided essential supplies to the vessel, and it was quickly established that the explosion had taken place in the aft harmonic filter (HF) room, situated within the aft main switchboard. The aft main switchboard was isolated, main generators were restarted and the ship was able to resume passage at 0523, subsequently berthing in Barcelona at about 0900. No one was injured.

The accident caused extensive damage to the aft HF and surrounding structure. Two water-mist fire suppression spray heads were activated, one in the aft harmonic filter room and the other in the aft main switchboard room.

The explosion was triggered by deterioration in the capacitors in the aft HF. Internal arcing between the capacitor plates developed, which vaporised the dielectric medium causing the internal pressure to increase, until it caused the capacitor casing to rupture. Dielectric fluid vapour sprayed out, igniting and creating the likely conditions for an arc-flash to occur between the 11000 volt bus bars that fed power to the aft HF.

A current imbalance detection system, which was the only means to warn against capacitor deterioration, was found to be inoperable, and it was evident that it had not worked for several years.

The electrical disturbance from the capacitor failure caused its circuit breaker to open and isolate the aft HF from the electrical network. It was not possible to determine the exact cause of the subsequent blackout because the option for storing historical data concerning blackouts was not chosen at build. However, it is considered most likely that the disruption within the aft HF at the time of the accident caused general instability in the electrical network which could not be contained and led to the generators shutting down.

Lloyd’s Register (Europe, Middle East and Asia) (LR) has been recommended to take forward proposals to the International Association of Classification Societies to:

• Establish a requirement for all new vessels fitted with harmonic mitigation equipment to model the effect of its loss and provide data to crew so that appropriate corrective action can be taken in such circumstances.

• Require on-line or periodic monitoring of harmonic distortion of voltage on all vessels with high voltage power systems to give early warning against potential problems.

• Develop requirements to detect and mitigate against the failure of high-energy storage devices and to ensure that protection devices of critical items are fail safe.

The Maritime and Coastguard Agency has been recommended to produce specific guidance regarding the harmful effects of excessive harmonic distortion in electrical networks and to update the Code of Safe Working Practices for Merchant Seamen to raise awareness about the hazards of arc-flash in high voltage equipment.

QM2’s manager, Carnival UK have also been recommended to: improve the standards of protection against the effect of harmonic distortion and component failure; and, to


review the machinery alarm systems fitted to QM2 in order to identify and prioritise those alarms which indicate failure conditions that could significantly affect the safety of the vessel.

Photo courtesy of Jörn Prestien.

(Extracts taken from: “Report on the investigation of the catastrophic failure of a capacitor in the aft harmonic filter room on board RMS Queen Mary 2 while approaching Barcelona 23 September 2010. VERY SERIOUS MARINE CASUALTY REPORT NO 28/2011 December 2011” available from http://www.maib.gov.uk/publications/investigation_reports/2011/qm2.cfm, along with a set of Annexes.)Editor – I find it interesting that they had a procedure for checking and recording the current monitors on the harmonic filter capacitors, but no procedure for what to do when their readings were wrong!

832 Radar interfered with early pacemakers

Dan Hoolihan: Also I think you mentioned to me that in your career you did some work with pacemaker companies and, in general, what kind of testing did you do on those and what kind of results were you looking for?

Jim Toler: Okay. Our introduction to that came through a company called Cordis, a pacemaker manufacturer in Miami, that I am not sure is still in business. But a Dr. Peter Harjean came to Georgia Tech looking for help. His concern was the possibility that pulsed radar systems might, in some way, alter the pulse of an implanted pacemaker. So, Peter made it possible for me to go to a number of medical conferences and meet pacemaker manufacturers. He took me there and introduced me to them. They, then, began to bring their pacemakers to Georgia Tech for EMI or EMC evaluations.

We struggled with how to test them. Out in just the air is not anything close to their normal installation location. So we devised a solution of saline to kind of represent, at least a composite, of body tissues and put them in a saline solution and put the lead out horizontally. We had a number of different high-powered radar systems at Georgia Tech so we exposed them to that environment in that kind of a solution. Interestingly, the first test involved a unit that was the largest — world’s largest — sales unit. In terms of sales volume it was the world’s best pacemaker. When we turned on the first radar, the pulse rate of the radar altered the pulse rate of the pacemaker.

Dan Hoolihan: Not so good.

Jim Toler: So we began working then with pacemaker design as well as pacemaker testing. The design problems were not overpowering, they basically involved

conventional filtering and shielding, but it had to be done in a biologically compatible [way] with tissue. That all had to be a consideration. So, we wound up with a rather extensive testing program for pacemaker manufacturers, both here and abroad. It was a learning experience for all of us and I made some very good friends in the process.

Dan Hoolihan: Did you also, then, get involved with the, for example, microwave oven issue? Microwave ovens and pacemakers?

How was your research with radars related to that?

Jim Toler: The microwave oven is, of course, a continuous wave field, not a pulsed wave field. So we had suspicions from the beginning that their effect might not be as great from microwave ovens. Although, those were the things that were feared at the time. But, we had an array of microwave ovens, and the tests began with the door closed. Then the door was opened by a certain amount and radiation levels went up, of course. Then opened by more and more. And pacemakers weren’t, generally, interfered with by microwave ovens. We pretty well proved that and established that point and relieved some of the concern with the microwave oven exposure. It was a public concern at the time, but not so much from technical or engineering point of views.

(Extracts taken from: “Interview with Jim Toler at the 2013 IEEE International Symposium on EMC” by Dan Hoolihan under the pen name “Espresso Engineering”, published in the 2014 IEEE Electromagnetic Compatibility Magazine – Volume 3 – Quarter 1, available from http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6798791)

833 Pennsylvania Voting Machine Malfunction EMI Related?

The recent election night proved to be a test for even the most determined voters. In addition to the long, slow-moving polling lines and the haphazard solutions put hastily into place for hurricane-ravaged areas of the Northeast, voters were also subjected to electronic voting machine malfunctions in several states across the country. In Pennsylvania, a voting machine was “taken out of service” after a YouTube video published by user “centralpavote” revealed the machine’s touch screen incorrectly registering votes for President Barack Obama as votes for Republican presidential candidate Mitt Romney.

The video submitter explains in the description section for the video that he attempted to select the checkbox beside President Obama’s name several times and each time, Romney’s name was highlighted instead.

“Being a software developer, I immediately went into troubleshoot mode. I first thought the calibration was off and tried selecting Jill Stein to actually highlight Obama. Nope … I asked the voter on either side of me if they had any problems and they reported they did not,” he said.

According to Alfred Poor, a display technology expert and a contributing editor with Information Display, many electronic devices equipped with a touch screen utilize a technology known as “projected capacitance” that relies on the build-up and exchange of an electrical charge between two conductors and “the fact that an electromagnetic field ‘projects’ above the plane of the conductive sensor layer.”

Even covering the touch module with a sheet of glass will not inhibit its ability to sense when a conductor is near. Poor explains that “when you touch the screen with your finger, it steals a little of the charge from each layer of conductors at that point … because each conductor is checked separately, it is possible to identify multiple simultaneous touch points.”

However, Poor cautions that the system of conductors “is susceptible to electrical noise from electromagnetic interference” and can misread which signals are from actual touch points, resulting in possible unintended performance of the electronic device.

At this time, officials have not determined the cause of the electronic voting machine malfunction in Pennsylvania.

(Taken from www.interferencetechnology.com/pennsylvania-vot ing-machine -malfunction-emi-related, 11/08/2012. For more information, visit The Raw Story: www.rawstory.com/rs/2012/11/06/pa-voting-machine-taken-out-of-service-for-flipping-votes-to-romney-report and PC Advisor (http://www.pcadvisor.co.uk/news/digital-home/3405657/how-it-works-technology-of-touch-screens/).

834 LED street lamps interfere with TV and radio in Japan

Actually, in 2010, poor reception of analogue TV and audio broadcasting occurred after LED lamps were installed in a shopping street in Japan [2].

(Taken from “Measurement and Modelling of Electromagnetic Noise from LED Light Bulbs” by Y Matsumoto et al in the 2013 IEEE Electromagnetic Compatibility Magazine – Volume 2 – Quarter 4, available from http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6714699. Reference [2] is [2] S. Kanno, N. Hirasawa and Y. Akiyama, “A study on the correlation between common mode voltage measured by using CDNE and radiated electromagnetic field strength emitted from LED bulbs>>, IEICE Tech. Rep., EMCJ 2011-12, pp. 13-17, Dec. 2011”.)


835 Goodreasonsforusingfibre-optical cables to solve industrial EMI

Fiber optic solutions are immune to electromagnetic interference (EMI), spikes, surges and ground loops. The data isn’t traveling along a copper wire; it’s carried by a beam of light. This is invaluable in industrial applications, for example, where the electric motors on the machinery can generate powerful magnetic fields. Wi-Fi and cellular networking confer similar advantages.

But remember that extending your data communications range via copper wire increases the risk for unwanted electrical events. The greater the distance between connected devices, the more likely it is that they will have different building ground references and the associated risk for ground loops. If the cable is installed in an industrial environment and passing machinery along the way, greater range also creates more opportunities for EMI.

Copper wire networks should be protected with surge suppression and isolation. Surge suppressors limit spikes between the signal and ground line and should be deployed as a first line of defense on power supply lines. Current models can be DIN rail mounted or connected directly to a cabinet, with surge protection ratings of up to 39 kA and less than 1 ns response time.

But when the ground line rises, as it does in ground loop events, you’ll need isolation. Isolators convert data signals either to pulses of light or an electrical field, and then back again. Spikes and surges are stopped at the isolation zone. Isolators protect power lines by transforming VDC power to AC, then back again.

(An extract from: “Five options to extend reach of your Ethernet network” by Mike Fahrion, who is the director of product management at B&B Electronics www.bb-elec.com, published in the Industrial Ethernet Book Issue 79 / 46, November 2013, pages 36-37, available at http://www.iebmedia.com/index.

836 US Navy problems with EMI in 1955

Radiofrequency interference (RFI) is caused by some machine tools and portable tools, as well as by induction heaters and RF stabilized arc welders. The newer types of electronic-controlled machine tools can be the victims of RFI. It is a coming problem in the metalworking field, and forebodes trouble for those who ignore the possibilities. Although there has been much work done on interference for many years, the machine-tool phase of RFI started about 1½ years ago…

By the time radio interference from welders and induction heaters became a recognised and fairly well controlled problem, Navy engineers working with highly sensitive

receiving equipment found that something was still causing trouble.

Interference can be generated by any number of electrical disturbances – both natural and man-made. But this specific interference was traced to certain kinds of electrical equipment associated with some machine tools.

MANY FORMS

Interference can take many forms, and can be caused by a wide range of electrical devices, including regular radio broadcasting and receiving equipment. However, there are few cases where broadcasting stations or amateur transmitters are major offenders because each is assigned its own frequency or band on which to operate. If the station strays, the operator is sure to hear about it.

The source of most of the trouble caused by machine tools is from electrical devices which produce current surges that radiate on frequencies used by regular broadcasters or the Navy.

These can be sparks between switch contacts, hums from induction mechanisms, static from buzzers, and other similar racket. Much of this is simply side effects from the mechanisms; not particularly desirable to the machine owner, but doing (he may think) no harm.

But it does. Generated RFI is transmitted like a regular radio signal, and can be received by regular radio equipment.

DISTANT DISRUPTION

An interference signal from an industrial plant may ruin ground-to-air communications at an airport many miles away. The pilot of a plane using ILA (Instrument Landing Approach) or GCA (Ground-Controlled Approach) would be helpless if uncontrolled interference were to blanket out his communications.

There is one case on record, among many, where an electronic device in an Oregon plant disrupted air-to-ground communications in Georgia.

SPARKING

Most “electrical noise” is caused by sudden changes in the flow of electricity, sparking, or current surging – which often produce undesirable effects. If sparking is designed out of the system, control devices can be simplified.

One good example of this is in fluorescent lamp starters, long a source of erratic RF noise and a product that needed improvement. One small company, working on fluorescent lamp designs, developed an improved and RFI-free lamp fixture. It was found that lamps in this design lasted several times as long as ordinary fluorescent lamps and the company now sell them for applications where interference is undesirable.

Interference is not just a Navy problem,

although the Navy has done considerable research on the subject and is relatively well informed. The problem of interference affects many industries and many kinds of equipment.

CURRENT SURGES

For example, the Navy found that some of their computers came up with impossible answers to problems. After a lot of digging around, they found that arcing fluorescent lamps were sending current surges back into the power line, where they were picked up by the computing machines and added into columns of figures. The computing machines were what might be called extremely vulnerable in this case and it has been possible to redesign their control systems so that they do not pick up line interference and convert it into false answers.

There is a silly side to RFI, too. A New York paper reported that a hotel guest was almost convinced his room had a ghost. Actually, his hearing aid was picking up a radio call for a bellboy, sent out by the inside radio system at the hotel.

The hearing aid should not have been able to receive radio calls – it is supposed to be an amplifier, and no more. No doubt, it has long since been repaired and adjusted.

(Extracts taken from: “Radiofrequency Interference—A Problem of Automatic Machine Control” by Charles D. Emerson, Associate Editor, American Machinist and Leonard W. Thomas, Interference Reduction Section, Bureau of Ships, from Bureau of Ships Journal, May 1956, as adapted from American Machinist, November 7, 1955 – as republished in “Quasies and Peaks” in the 2013 IEEE Electromagnetic Compatibility Magazine – Volume 2 – Quarter 4, available from: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6714693.)

837 Effects of RFID emissions in Health Care

By early 2009, the auto-ID industry association hopes to publish a set of methodologies that can be used to determine the impact of tag and reader transmissions on medical devices, drugs, blood and human physiology.

“There have been a number of different studies or tests done [studying the effects of RF in health-care settings],” says Dan Mullen, AIM Global’s president, “and to the members of the REG’s credit, we have decided to create a set of test protocols that are repeatable and consistent that the industry can look at and use to determine whether there are any concerns or issues.”

Mullen cites several studies unveiled in July—particularly one conducted by researchers at Indiana University Purdue University Indianapolis (IUPUI) and by


RFID consulting and systems integration firm BlueBean, and another conducted by researchers at the University of Amsterdam’s Academic Medical Center in the Netherlands as part of a government research project, and published in the Journal of the American Medical Association (JAMA).

Both studies examined whether electromagnetic radiation from RFID systems would disrupt infusion pumps, EKG monitors and other medical equipment. Their findings, however, differed. The IUPUI/BlueBean study discovered no problems with electromagnetic interference (EMI) (see New RFID Study Finds No Interference With Medical Devices), while the Dutch study did find incidents of EMI by RFID on critical-care equipment in a non-clinical setting (see Researchers Warn RFID May Disrupt Medical Equipment).

“At a certain point, we realized we needed to do something about this,” says Craig Harmon, the REG chairperson, and president and CEO of Q.E.D. Systems. Harmon says he and others had received a number of calls regarding the IUPUI/BlueBean and University of Amsterdam studies, and that industry concern greatly spurred action by AIM Global. The organization initially felt the U.S. Food and Drug Administration (FDA) should lead the effort, but later changed its mind upon meeting with FDA representatives who acknowledged such an initiative could

take two or three years.

“We can’t afford to wait that long,” Harmon says. “I’m not aware of anyone who is saying RFID is being banned in hospitals, but I have heard—and this is more rumor than being able to point to one specific example—that some health-care organizations are delaying the use of the technology.”

The REG will develop three test protocol suites: one for medical devices (implantables and wearables); a second for clinical instrument susceptibility; and a third for pharmaceuticals, biologics, blood products and human physiology. The protocols will initially focus on radio frequency identification systems based on any of 11 different RFID standards, including ISO 11785 (which employs the 125 kHz frequency band), ISO 14443 and ISO 15693 (13.56 MHz), and ISO 18000-6C and EPC Gen 2 (860-960 MHz), as well as IEEE 802.11, or Wi-Fi (2.45 GHz).

To accomplish its mission, the REG will collaborate with three leading universities in the field of RFID: Georgia Institute of Technology, the University of Pittsburgh and the University of Texas at Arlington. The group hopes to have test protocols ready in the next six months or so, Harmon says, but the effort will take time.

Once the REG completes its work on the

test protocols, it plans to submit them to the FDA for comment and approval. AIM then hopes to make the test protocols available to testing facilities, labs and universities. Details are still being worked out in terms of how the protocols will be licensed, but Harmon says that under collaboration agreements, the protocols will be owned by the companies and university participants directly involved in their development—though who these would be has not yet been determined.

(Extracts taken from: “AIM Global to Develop Protocols for Testing Effects of RFID Emissions in Health Care” by Beth Bacheldor in the RFID Journal, www.rfidjournal.com/articles/view?4384.)

Banana Skins

Banana Skins are kindly compiled for us by Keith Armstrong.If you have any interesting contributions that you would like included, please send them together with the source of the information to: [email protected]

Although we use a rather light hearted approach to draw attention to the column, this in no way is intended to trivialise the subject. Malfunctions due to incorrect EMC procedures could be life threatening.

EMC for Luminaires … the ongoing struggle!The Scenario….New technologies can lead to more efficient products.But some can be electrically noisy, causing serious radio interference.

The Problem….LED lamps are a classic example.Whilst many have been designed to be ‘quiet’, there are many that do cause interference well above legal limits(EN55015). These have led to consumer complaints, product withdrawals and action by Trading Standards, withconsequent damaged reputation for the supplier.

The Solution….Always test products for EMC. Low cost EMC emissions test equipment can be used in-house to quickly andeasily measure the emissions and ensure compliance with the standards.

Why take the risk? In-house testing is the logical and cost effective answer.

Laplace Instruments Ltd has developed ALECS*, a complete integrated system designedspecifically for the EMC testing of Luminaires according to EN 55015.* Automated Luminaire Emissions Compliance System

See www.laplace.co.uk or call +44 (0) 16 92 40 20 70


John Woodgate’s ColumnUsingaNotifiedBodyThe involvement of ‘third parties’ in the EMC compliance process is still not fully understood by some. It is quite clearly explained in the Guide to the 2004 Directive and isn’t substantially changed by the 2014 Directive (which cannot yet be cited in DoCs until at least one Member State has passed it into state law). However, the 2014 Directive is much more meticulously worded (except in one case!). We are promised a Guide to the new Directive but it may be a while coming.

The position is actually set out in formal (but not impenetrable) language in Annex II and Annex III of the 2004 Directive. The main point is that the involvement of a Notified Body is an option, however the manufacturer chooses to demonstrate conformity of the product. Previously, a Notified Body had to be involved unless all the applicable standards were wholly applied.

Annex II covers the ‘in-house’ procedure, where the manufacturer (or ‘authorised representative’) does not involve a Notified Body (but may have tests done by a test house). The most important requirement is the production and maintenance of an EMC Assessment. This is intended to document the EMC characteristics of the product, which leads to a documented decision on which standards apply and which phenomena need to be assessed and thus which tests should be carried out. For example, an analogue product not using any frequency above 150 kHz (9 kHz for some product types) need not be tested for emissions, but probably does need to be tested for immunity to some phenomena, but not by any means all of the IEC 61000-4 series Basic standards.

The EMC Assessment is your ‘get out of jail’ card if market surveillance challenges the conformity of your product, so it had better be comprehensive, truthful and convincing, without being a ‘three-volume novel’. That means it needs time spent on it, not just dashed off in a hurry. It might even be helpful to have it translated into the languages used by your more exacting export customers, because it demonstrates that you take the subject very seriously.

If your novel product has features that cause you concern about how to demonstrate conformity (e.g. it’s a Thursday detector for a time machine), then you are free to use the Annex III procedure. In this case, you ask the Notified Body to comment on your EMC Assessment (no, you can’t escape producing it). You have, and this is particularly not well-known, the right to ask for only specified parts of the Assessment to be considered, not necessarily all of it. For example, you may be quite sure there is no doubt about conformity with IEC 61000-3-2 and -3.The Notified Body issues to you, the manufacturer, either a compliance certificate (this is not a document addressed to the

authorities) or a deficiency report. The compliance certificate then becomes part of the EMC Assessment.

The subject is treated in far more depth in Annexes II and III of the 2014 Directive, although the essentials may be considered unchanged. Terminology and texts have been revived from earlier Directives. The ‘assessment’ has been conceptually separated from the ‘technical documentation’, which seems unnecessary, because the assessment would be useless if it were not documented, and that documentation is the ‘technical documentation’.

There is now, in Module A of Annex II, a bulleted list of essential constituents of the technical documentation:general description;• manufacturing drawings, parts lists and circuit diagrams

(termed ‘schemes’);• explanations, where necessary, of the drawings, etc.;• list of applied standard and what has been done if standards

were not applied in full; • test reports;• results of design calculations (!) and ‘examinations carried

out etc.’;

NOTE 1: In my opinion, this last point is highly onerous and very badly worded. It is totally unreasonable to expect a record of the calculation of every component value and of every aspect of circuit performance. Also ‘examinations carried out, etc.’ is an open-ended requirement. The expression ‘etc.’ should not appear in any regulatory document.

NOTE 2: The documentation may well be very similar to that required by the LVD or another applicable Directive, so it can serve more than one purpose. There is no objection to the documentation containing both EMC and safety assessments and one set of drawings and parts lists.

Annex III is divided into Parts A and B. Part A consists of ‘Module B: EU type examination’ and gives the procedure for involving a Notified Body. It is not required (it can even be interpreted that it is prohibited) for the Notified Body to examine a sample product. Only one Notified Body may be involved; the manufacturer has to attest this. The Notified Body has to document the assessment procedure it applies to the specific product (not a ‘generic’ document). It is not permitted to disclose the report it submits to the manufacturer (except that the authorities have a legal route to demand disclosure). The content of the type examination certificate is specified. If a certificate is refused, the reasons must be documented.


Notified bodies will, in future, be required to be fully informed on changes to standards and other similar document, and notify holders of certificates if changes might affect their validity. Equally the manufacturer will have to keep the Notified Body of changes to the product that might affect conformity. Notified Bodies will have to inform the authorities of all certificates issued, modified, refused, withdrawn, restricted (meaning?) or suspended, and make the information on certificates refused, withdrawn, restricted (or suspended, available to all other Notified Bodies, and, upon request, supply details of any certificate issued or modified.

Part B of Annex III explains what the manufacturer has to do, in terms of manufacturing processes and monitoring, to ensure that production samples of the product remain in conformity, at least up to the time that physical control of them passes out of the hands of the manufacturer.

It is important to bear in mind that the Directive is not the law; it is the transcription of it into laws in the Member States that is legally valid. So there is scope for ‘lost in translation’ effects or, perhaps more significantly, ‘gained in translation’ – this is where wording is considered obscure and is ‘clarified’ by making a requirement more stringent. Known also as ‘gold plating’, it has been alleged to have taken place in Britain, but we are assured that there are now safeguards in place to prevent it.

It seems to me that there should also be a safeguard against ‘lost in translation’ or ‘garbled in translation’. This can be achieved by translating back from the target language into the original language. Maybe the Commission already does this, and probably we will never know.

‘EMC-quiet’ signal sources and receiversDescending from the philosophical heights of the Directive to the crude hardware, there is often a need in product development, evaluation or testing, for a signal source that emits only the wanted signal or a receiver that is highly immune to everything but the wanted signal. Such devices are rarely commercially available and if they are, they may be costly. So, do not rule out DIY. It is quite practicable to put, say, a DVD player in a diecast box, with a simple analogue power supply and filtered connectors. In some cases, even filtered connectors can be unobtainable but may be built from available parts. Copper foil is often your friend.

Next timeQuite frankly, I have no idea. It may come as much of a surprise to me as to you. But assuredly, there will be something.

• EMC 3m compact, 3m, 5m & 10m solutions

• Antenna measurement chambers

• EMC Emissions & immunity

• High-performance shielded rooms for EMC, Tempest, EMPP and MRI

• Masts, turntables & controllers

• Mode stir technology

• High-performance absorbing materials

Absorbers & Chambers Made to Last.

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Know Your StandardsNew Legislative FrameworkThe Department of Business, Innovation and Skills circulated a notice in April, part of which reads:

As you will probably be aware, eight EU New Legislative Framework (NLF) alignment Directives have now been published in the Official Journal. The NLF implements the text of EU Decision 768/2008/EC and makes reference to Regulation 765/2008/EC. Together this creates a more coherent legislative framework for the marketing of products in the EU Internal Market; providing improved traceability and clearer requirements on economic operators, greater accountability in the designation and consistency of performance between notified bodies, and the alignment of conformity procedures and commonly used definitions within the conformity assessment process. The NLF does not revise sector-specific elements of existing Directives; no changes have been made to the scope or essential requirements.

The Directives aligned are:

• Explosives for Civil Uses

• Simple Pressure Vessels (SPV)

• Electromagnetic Compatibility (EMC)

• Non-Automatic Weighing Instruments (NAWI)

• Measuring Instruments (MID)

• Lifts and Safety Components for Lifts

• Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres (ATEX)

• Electrical Equipment Designed for Use within Certain Voltage Limits (LVD)

Member States have two years to transpose these Directives. In the UK we plan to undertake this work as a package to minimise the burden on all those involved. I will contact you again soon to provide further details of how we will take this forward, which will of course include an appropriate formal consultation on implementation of the aligned Directives.

MaintenanceofIEC61000-4-seriesBasicstandards4 SC77BMT12Most of these standards are the responsibility of MT12 of IEC SC77B, but some are ‘owned’ by the other sub-committees of TC77. MT12 is extremely active; the members produce a large number of document for discussion at meetings.

MT12 met in February 2014, with the following results.

IEC 61000-4-2A very long list of potential improvements was discussed; some 16 topics were mentioned.

IEC 61000-4-4A shorter list of five items was discussed for this standard, including improved calibration procedures and the future of the test at 5 kHz.

IEC 61000-4-5This was at the FDIS stage, so certain items could not be progressed until the next maintenance cycle, which has already started. A request for an Interpretation Sheet could not be accepted because the subject does not concern IEC 61000-4-5 but one or more product standards. But informative text may be added in the maintenance process. A request to exempt some products from testing at all levels of the disturbance was not accepted. The committee reiterated that all-level testing is always required. This may cause considerable design problems for some products.

IEC 61000-4-9This standard hasn’t been changed since 2001, and it is now under extensive revision. A number of topics are being studied, and some reported results are inconsistent, or appear so. A CD was circulated in February 2014.

IEC 61000-4-10A number of very significant improvements are required. A CD is being drafted.

The MT will continue to hold two meetings a year.

4 SC77AIEC 61000-4-11WG6 is revising this standard and a CD is forecast for December 2014. Questions have been raised about the very fast rise and fall times required of the test generator, as they can affect cost considerably. The purpose of these specifications may be to restrict the inductance of the test source: The maximum rise or fall time (1% to 90% amplitude) is 5 µs and the non-inductive test load is 100 ohms. Using the rule that the rise time is 2.2 times the time-constant L/R, the maximum permissible source inductance is 220 µH. A finite inductance is usually required for stability if the source is an amplifier. But the inductance of the IEC TR 60725 reference supply impedance for 230 V 50 Hz is 796 µH. The test generator has to simulate higher-current supplies with less inductance but few EUTs are non-inductive loads.


Know Your StandardsIEC 61000-4-16A DC was circulated about the maintenance of this standard. A number of National Committees expressed support for an early revision, but some proposals were rejected by the Secretariat. Discussions could become interesting.

IEC TR 61000-4-38 Calibration and verification protocol for flicker compliance test systemsThis is a new TR, produced by WG2. It should help to reduce the possibility of different test houses returning different results on the same EUT.

4 SC77CIEC 61000-4-36 (IEMI [Intentional EMI] immunity test methods)This document has reached the CDV stage. It is quite long – 79 pages. Let us hope that its provisions seldom need to be verified as effective in practice.

Other standards4 CISPR/ACISPR 16-1-1Fragment 2 of Amendment 2, on the use of an external preamplifier with a measuring receiver, has reached the first voting (CDV) stage. The advice is not to do it unless absolutely necessary and then to be very careful to avoid overloading the receiver.

CISPR 16-2-3CISPR/A WG2 has produced a DC (Document for Comment) on EUT size specifications in CISPR publications. These have traditionally been developed on the basis of the dimensions and characteristics of the test fixtures, so differ between standards.

The discussion and proposed solutions extend to 11 pages, which si long for a DC. It includes a proposed Informative Annex to explain the background in terms of four criteria for EUT size. The smallest size resulting from considering these criteria is definitive. The criteria are:• limiting field-strength conversion effects between short-

distance measurements and those at the distance specified in the standard;

• limitation of near-field effects;• limitation of effects due to antenna directivity;• limitation of effects of EUT coupling to absorbing material.

4 CISPR/BTask Force (TF) on wireless power transferA DC was circulated on this subject and the report has been circulated. 12 experts have been appointed to the TF, which will meet for two days in June 2014. The TF will develop requirements to be added to CISPR 11 and may provide advice to other committees studying WPT.

Next timeWho knows? The number of meetings, especially BSI meetings, still tends to reduce, as work-loads increase and budgets decrease. But the brighter economic signs may reverse this trend at some future date.

J.M.WoodgateB.Sc.(Eng.),C.Eng.MIETMIEEEFAESHonFInstSCEEmail: [email protected]: www.jmwa.demon.co.uk© J.M.Woodgate 2014

Advertise your EMC vacancy hereThousands of people in the UK have received this Journal and we have an unlimited worldwide readership through the compliance-club.com website. So this is the perfect place to advertise your EMC vacancies, whether that be in engineering, management or sales.

the journal Email your job advertising needs to:

[email protected] call John Davies on: +44 (0) 7506015791


PRODUCT GALLERYNew V9000 trimmers for MRI coil designs

For over 50 years, Voltronics has been providing variable trimmer capacitors to the electronics industry. In the field of Magnetic Resonance Imaging, Voltronics have developed the broadest line of non-magnetic products in the world. The V9000 series is the newest, smallest, high voltage trimmer capacitor.

The V9000 Sapphire trimmer capacitor is unique in design. It is truly sub-miniature at just 0.64 inches (at minimum capacitance) in length, but offers the highest working voltage rating (2 kV) for its size – whilst delivering a capacitance range of 1 to 12pF. Sapphire is ideal for precision trimmer capacitors as its dielectric constant is extremely stable, measuring below 0.0003 up to 10 GHz, and is chemically inert; totally moisture resistant and mechanically strong.

These trimmers have a high Q (3000 min at 100MHz); DC working voltage of 2000V and DC withstand of 3000V. They are also compatible with SAC 305 reflow processing.

T h e V 9 0 0 0 S e r i e s i s specifically designed for the MRI industry where its size, power, capacitance range and affordability make it the preferred choice for the next generation of coils. Due to the severe non-magnetism requirements this industry requires we use only materials that exhibit no measurable magnetism – commercial brass and plating materials

are not acceptable. Our strict traceability and testing regimes ensure this essential parameter.

Note: Dielectric Laboratories (DLI) , Novacap , Sy fer Technology and Voltronics have come together into a single organisation, Knowles Capacitors. This new entity has a combined history exceeding 175 years and is a division of Knowles Corporation of USA,

an independent publicly traded company.

For more information, contact: Peter Scutt [email protected]

Knowles Capacitors, Old Stoke Road, Arminghall, Norwich, Norfolk NR14 8SQ UK

T: +44 (0)1603 723310 F: +44 (0)1603 723301 www.knowlescapacitors.com

Touch to Test – IMU4000, the newest arrival

IMU4000 completes our compact immunity family. Based on the user friendly touch panel and colour graphics interface, IMU4000 builds on the success of the EMC PARTNER Operating System (EPOS).

Modular architecture is a time and money saving

feature, enabling on-site upgrades of ESD, EFT, CWG, AC/DC DIPS, INTERRUPTS, VARIATIONS and COMMON MODE circuits.

Easy navigation using the touch panel or rotary knob is supplemented by the ability to change parameters during test. Surge voltages up to 4kV combined with EFT up to 5kV make IMU4000 the automatic choice for manufacturers and developers seeking a flexible and reliable test solution.

Fully integrated into the all new TEMA 3000 software with DSO control and custom report generator, IMU4000 is the perfect addition to any test laboratory.

EMC PARTNER IMU family compact immunity testers are available as 4kV, 6kV and 8kV models.

For more information, contact: David Castle E: [email protected] T: 01494-444255 F: 01494-444277 www.emcpartner.co.uk


Murata develops world’s smallest combined proximity and illuminance sensor

Murata today announced what it believes to be the world’s smallest combined proximity and illuminance sensor. The surface mounted LT-1PA01 device measures just 3.05 x 2.10 x 1.10 mm and integrates both an optical proximity sensor and an illuminance sensor. The proximity sensor uses a photoreceptor to measure the distance to an object based on the amount of returned light. Another photoreceptor is used to detect the amount of ambient brightness. Such sensors are widely used in smartphones to darken the screen when the phone is near the user’s face during a call or to increase the brightness of the screen’s backlight when used outdoor.

PRODUCT GALLERY

Features• World’s smallest size: 3.05 x 2.10 x 1.10mm

• Low power consumption: 80µA during proximity sensing (sleep time: 800ms)

• Effect of distance between cover glass and sensor: No effect up to 5mm

• Illuminance sensing angle: ±45° at 50%

• Sensing distance: 70mm with gray card

Applications• Smartphones / tablets

• Office equipment

• Home appliances

Electric characteristicsOperating voltage: 2.7 to 3.6 [V]

For more information, contact: info@ murata.eu www.murata.com

Methode Electronics, Inc. Announces New Medical Grade shrinkMate™ Cable Shielding

Chicago, IL – May 30, 2014 – Methode Electronics, I n c . ( N Y S E : M E I ) , a global developer of custom engineered and application s p e c i f i c p r o d u c t s a n d solutions, today announced the release of the new medical grade shrinkMate™ shielding heat-shrink tubing. Using clear medical grade polyester, the lightweight tubing shrinks over the object when heat is applied and forms a perfect conductive seal around the object, delivering EMI, RFI, and ESD shielding without the use of solder.

In the sensitive medical equipment environment, EMI, RFI, and ESD leaking can lead to disturbances which may endanger the health or life of patients. It is therefore of the highest importance that leakage does not occur, and demanding standards are enforced on medical device

manufacturers. shrinkMate™ cable shielding can help meet the tough requirements of this industry by providing easy-to-apply shielding at a common point of leakage – the cable to connector joint.

The conductive tubing shrinks with a heat gun, oven, or any other conventional heat source, and when the tubing is set, the inner conductive layer provides an electrical connection between the outside surfaces of the objects that are joined by the tubing. Connections can easily be made between

components of various sizes and shapes, and between solderable and non-solderabale surfaces.

shrinkMate™ cable shielding tubing is also available in MIl-I-23053/5 polyolefin tubing. All shrinkMate™ products are RoHS and REACH compliant.

For more information, visit: http://www.methode.com/products/shrinkmate.html.


PRODUCT GALLERYPatent makes waves in industry

In a move which will further solidify its status as a leading manufacturer of high quality power equipment, REO UK has obtained a patent for the water cooling and encapsulation of chokes. Used in railway, renewable and regenerative applications, the new chokes improve size and efficiency, helping customers make further energy savings.

Chokes, typically used with variable speed drives for smoothing, regulating and limiting current, provide greater control and reduced energy consumption in motor applications. The last few years have seen an industry wide shift from air cooled to water cooled chokes, as a result of their increased longevity as well as lower operating temperatures and improved return on investment.

In order to cater for the varied and demanding design and power requirements of its customers, REO has successfully obtained a patent on an improved method of water cooling and encapsulation, implemented in a range of chokes designed for various low and high power applications.

The resultant state of the art choke is fully encapsulated, with water pockets forming an integral part of the windings and of the resin based encapsulation. This makes the unit more efficient at heat management whilst simultaneously removing hot-spots. This means the choke can be designed for a smaller safety factor, as variables are better known.

A further benefit of the design is the ability to achieve a high class of ingress protection, such as IP66 certification, further widening usability. For instance, use on train locomotives is possible, where weather sealing is necessary to face the high speed and harsh conditions.

For small applications up to 30kW, REO manufactures an encapsulated and cold plate mounted choke, which includes integral coolant channels. The design is optimised to permit precisely focussed pinpoint cooling and provides simple integration into existing cooling systems.

For larger, more complex applications, REO manufactures a choke with an open construction. Here, cooling profiles that are integrated in the windings are able to dissipate heat directly at the point of generation in the most efficient way possible.

“We are continuing to work with customers in rail, renewable and regenerative applications to help put energy back into the national grid as well as ensuring that the energy we create is cleaner and more sustainable,” said Steve Hughes, managing director of REO UK. “The patented water cooled chokes are more efficient and contribute to us achieving this goal by helping our customers reduce their energy costs and achieve a higher return on investment.”

Editor’s note: If you want to ensure you keep up to date with press material, opinion focussed blog content and case studies from REO UK, you can subscribe to receive the company’s blog posts by e-mail at http://www.reo.co.uk/blog/.

For further information contact: Steve Hughes or Michelle GillamREO (UK) Ltd, Units 2-4 Callow Hill Road, Craven Arms Business Park, Craven Arms, Shropshire, SY7 8NTE: [email protected] T: +44 (0)1588 673411F: +44 (0)1588 672718www.reo.co.uk


The new R&S RTE oscilloscopes from Rohde & Schwarz

Ease of use combined with powerful analysis tools

R & S R T E d i g i t a l oscilloscopes offer fast and reliable solutions for everyday T&M tasks such as embedded design development, power electronics analysis and general debugging. Users benefit from features such as high sampling and acquisition rates and good signal fidelity. A comprehensive set of measurement and analysis tools deliver fast results and the high-resolution touchscreen makes the R&S RTE very easy to use.

Munich, February 26, 2014 — The new R&S RTE from Rohde & Schwarz is available with bandwidths from 200 MHz to 1 GHz. An acquisition rate of more than one million waveforms per second helps users find signal faults quickly. The scope’s highly accurate digital trigger system with virtually no trigger jitter delivers highly precise results.

The single-core A/D converter with more than seven effective bits (ENOB) almost completely eliminates signal distortion. With a sampling rate of 5 Gsample per second and a maximum memory depth of 50 Msample per channel, the R&S RTE can accurately record the long signal sequences required when analyzing the data content of serial protocols such as I2C and CAN.

Users performing complex tasks will especially appreciate the high measurement speed of the R&S RTE. Mask tests, for example, quickly return statistically conclusive results. The highly responsive, spectrum-analyzer-like FFT reliably detects even sporadic signals, making the R&S RTE ideal for EMI debugging during product development.

Thanks to the high-resolution 10.4” XGA touchscreen, users can intuitively perform their daily T&M tasks. For instance, they only have to swipe the screen to access saved instrument setups. And they can simply “drag & drop” waveforms to arrange them on the screen. Realtime miniature views of the signals on the edge of the screen allow users to always see what is happening.

Dialog boxes are opened as semi-transparent overlays over the active waveforms, which maintain their full size. Signal flow diagrams and forward and back buttons in the dialog boxes simplify navigation.

Innovative tools help users boost their productivity. The QuickMeas function simultaneously performs several measurements on a signal. Fingertip zoom allows users to simply swipe a signal’s zoom area to quickly view signal details. Tools are selected from a configurable toolbar.

Rohde & Schwarz also offers a wide range of dedicated application solutions for the R&S RTE, including trigger and decoder options for serial protocols, a mixed-signal option with 16 additional digital channels and a power analysis option. A broad probe portfolio rounds out the offering.

The new R&S RTE can now be ordered from Rohde & Schwarz with two or four channels and a bandwidth of 200 MHz, 350 MHz, 500 MHz or 1 GHz.

For more information visit:www.scope-of-the-art.com/ad/press/rte

PRODUCT GALLERY

The new Rohde & Schwarz oscilloscope


Rohde & Schwarz provides reliable test solution for eCall in-vehicle system modules

To ensure fast emergency response times to automobile accidents and save lives, automatic emergency call systems will be mandatory for all new vehicles in the EU starting in 2015. Rohde & Schwarz supports manufacturers today by offering a standard-compliant test solution for the wireless and GNSS-capable components of eCall in-vehicle systems.

Munich, February 19, 2014 — Rohde & Schwarz will demonstrate its compact eCall test solution for in-vehicle emergency call systems for the first time ever at Mobile World Congress. The setup consists of the R&S CMW500 wideband radio communication tester and the R&S SMBV100A vector signal generator with integrated global navigation satellite system (GNSS) simulator. This setup allows manufacturers and suppliers of automatic in-vehicle system (IVS) to perform reliable and reproducible end-to-end conformance tests on their eCall modules.

When an accident occurs, the IVS connects with a public safety answering point (PSAP) via the local wireless communications network and transmits a minimum set of data (MSD) that includes the GPS coordinates of the vehicle involved. The Rohde & Schwarz test solution enables users to verify whether their IVS modem can successfully initiate an emergency call, transmit the correct MSD and establish a voice connection with a PSAP.

Rohde & Schwarz developed the R&S CMW-KA094 eCall application software specifically for this application. The software simulates a PSAP and controls the R&S CMW500 emulating a wireless communications network in the lab. It also controls the GNSS simulator supplying the coordinates required for localization. The test solution is fully automated thanks to the R&S CMWrun sequencer software and can be used right away. The user can test the RF interfaces and GNSS receiver and also

check that the entire system is functioning properly.

With the advent of eCall, GSM and UMTS wireless communications technologies are now making their way into private vehicles. Rohde & Schwarz has spread its RF testing expertise to the automotive sector with its eCall test solution. The R&S CMW500 is a future-ready multistandard platform capable of testing RF interfaces such as WLAN, 2G, 3G and LTE for tomorrow’s traffic telematics modules. The R&S SMBV100A can also be used to test navigation systems and other applications that require position information. The GNSS simulator offers a range of flexible realtime scenarios with up to 24 dynamic satellites for GPS, Glonass, Galileo and BeiDou.

Rohde & Schwarz will display the setup at Mobile World Congress in Barcelona (hall 6, booth C40). The R&S CMW-KA094 eCall application software, R&S CMW500 and R&S SMBV100A are now available from Rohde & Schwarz.

For more information see the following Rohde & Schwarz application card: www.rohde-schwarz.com/ad/press/eCall

PRODUCT GALLERY

eCall data transfer principle

www.kemtron.co.uk+44 (0) 1376 348115 · [email protected]

RFI /EMI shielding gaskets& components

Kemtron-EMC 128x88.qxd:Layout 1 2/8/13 14:10 Page 1


PRODUCT GALLERY

ETL Launches New Components Mounting System

Compact and flexible design is already being used by prominent market leader in oil and gas sector.

Madley, UK. 21 May 2014. ETL Systems, a global designer and manufacturer of RF distribution equipment for satellite communications, has launched a new Components Mounting System (CMS) as part of its new line of RF equipment.

Designed with flexibility at its core, the 1U 19 inch chassis accommodates ETL’s Scorpion range of passive L-band two, four and eight-way passive splitters and combiners in any combination, as required by the operator. ETL’s in-house engineering team have designed the CMS unit to be versatile by giving users the choice to install the same components, a mixture of all three, or anything in between.

The f i rs t cus tomers to select ETL’s CMS include a prominent market leader in the oil and gas sector and a large European broadcasting project with multiple installation sites worldwide. The CMS continues to gain popularity in other applications including mobile VSAT, fixed satellite teleport and earth station feeds.

“The Components Mounting System is particularly ideal for VSAT transmit and receive applications because of its flexibility to accommodate different stacks and modules all within the one chassis,” said Dominic Overton, Components Sales Executive, ETL Systems. “The concept of the design was developed to address our

customer’s needs for equipment which houses components in a compact and neat chassis. Our compact design makes it the perfect solution for sites where space is at a premium. Users no longer need to have different mounting racks for each splitter and combiner but can install a variety of different components neatly in any combination they wish, just with this one system.”

The release of the CMS is accompanied by other new components products being made available by ETL. Their huge range of RF components now includes Ku and Wide band passive splitters and combiners, both of which are available in two-way, four-way or eight-way with 50Ω impedances and SMA connector types, offering consistently excellent RF performance.

“ETL is dedicated to constantly improving its huge range of RF components and our latest products enhance our offering even further,” said Andrew Bond, Sales Director, ETL Systems. “With a quarter of a century of experience in designing award-winning RF equipment, including rack mount systems and RF components, we can also custom design and build products in the event that our ‘off the shelf ’ range does not meet a customer’s specification.”

For more information, contact: visit them at the International Microwave Symposium 1-6 June at booth 809 or visit www.etlsystems.com Narda Safety Test Solutions GmbH

Sandwiesenstrasse 772793 Pfullingen, GermanyTel. +49 7121 97 32 [email protected]

Rapidly identify, precisely analyze, easily evaluate and intelligently localize interference in the radio spectrum.

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narda_ida2_EMC_EN_103x297:print14 10.03.2014 9:54 Uhr Seite 1


EM Simulation of Automotive Radar MountedinVehicleBumper

By Remcom - Electromagnetic Simulation Solutions

AbstractTrends in automotive safety are pushing radar systems to higher levels of accuracy and reliable target identification for blind spot detection and collision prevention assistance. Consequentially, engineers need to better understand how mounting brackets, fascia, paint color, and bumper assemblies affect the far field radiation patterns of 24 GHz and 77 GHz automotive radar systems. Long used for lower frequency (and longer wavelength) antenna-on-vehicle simulations, including vehicle-to-vehicle communication, electromagnetic (EM) simulation can now handle high fidelity analysis beyond the ideal 24 GHz and 77 GHz sensor itself, to include the antenna package and the automobile body features surrounding the device.

In this paper, a 24 GHz sensor is used to discuss differences between the simulation of a stand-alone sensor and one that is mounted in a vehicle. Efficient finite-difference time-domain (FDTD) EM analysis, combined with dramatic computation

acceleration via CUDA-enabled graphics processing units (GPUs), make Remcom’s XFdtd®, a fully arbitrary 3D EM simulation software tool, an optimal choice for the simulation of an antenna-in-system design with this level of complexity.

Design Challenges at High FrequenciesThe shorter wavelengths of 24 GHz and 77 GHz pose design challenges that are not present in applications at lower frequencies, like vehicle-to-vehicle communication at 5.9 GHz. At the sensor level, structures in the PCB layers become electrically large and can cause unexpected interference. Likewise, when the sensor is mounted in a vehicle, the thickness of the fascia can distort radiated waves and cause undesired reflections. Some of these issues lead to changes in the sensor’s design, while others are better addressed by providing guidelines to automobile manufactures. Regardless, engineers need a tool that permits a high fidelity analysis to be performed and allows them to ferret out issues in their design while considering all aspects affecting a sensor’s performance.

Figure 1 – XFdtd simulation of a 24 GHz sensor mounted in the rear bumper of a sedan provides the framework for the discussion in this paper.

Figure 2 – Time-domain fields show interactions within the sensor.


Radar is Inherently Time DomainRadar is an inherently time domain process: a signal travels out from a transmitter, reflects off of an object, and returns to the receiver. While much of radar design occurs at a systems level with mathematical signal processing concepts, signal integrity problems can occur on the local radar circuit board and adversely affect overall radar system performance. Simply looking at the frequency content of these unwanted current or voltage problem areas may not provide enough information to thoroughly design or troubleshoot the radar system.

FDTD EM simulation has the ability to show the motion of signals as a function of time. Tracking the source of a particular current or voltage coming into a problem area in the circuit can reveal the root source of a performance problem in a radar device. The problem might come from unwanted coupling among signal traces on the board. The problem might result from energy ringing down from the antenna or other high Q portion of the circuit. These time-dependent phenomena cannot be seen clearly with a purely frequency domain approach; time domain simulation is needed to find these types of problems.

Further, once the sensor is mounted to a vehicle, interference at the received antenna can make target identification difficult. This interference may be caused by a resonance setup in the bumper assembly or reflections from the mounting brackets. FDTD EM simulation and GPU computer technology now allow the inclusion of larger structures, such as the bumper or back end of an automobile, to be included in automotive radar device simulations. High fidelity EM simulations of 24 GHz or 77 GHz radar mounted inside automobile bumpers can help application engineers and their customers thoroughly troubleshoot antenna performance and how it changes with vehicle structure and materials during the design cycle.

The images in figure 3 compare electric fields as they radiate away from the sensor. Unlike the stand-alone case on the right, the case on the left shows the fascia trapping waves. This is undesirable because it distorts the transmitted fields and because the trapped fields reflect back into the receiver, causing interference.

ParameterizationExploresBeyondtheAntennaAutomotive radar design needs to analyze and simulate more

than the ideal frequency domain antenna characteristics alone. Packaging details close to the antenna as well as vehicle body features a meter or so away from the antenna also affect the antenna far field patterns and the radar system performance. Starting right in the antenna construction, the alignment of multiple layers (registration) during assembly can affect the performance of the antenna. The edge effects of a circuit board dielectric, mounting screws holding the circuit board to a package, and any package cover or radome over the antenna can alter the antenna radiation pattern or cause time domain reflections back to the antenna that don’t appear in systems level design. Moving beyond the automotive radar device packaging, the bumper and entire nearby section of the vehicle will also affect the antenna and radar system performance. Taking into account vehicle and bumper materials, shapes, dimensions, and device packaging creates many variables to explore in radar system design.

One approach to testing multiple dimensions of variation – bumper materials, paint coatings, and thicknesses – is via parameter sweeps in EM simulation. Most any quantity specified in a simulation can be done so using a variable and therefore swept over a range of values in an automated way. Parametric sweeps can vary geometries such as the mounting location of the automotive radar device horizontally along the bumper and around its curving corner. Nested sweeps varying more than one parameter at a time are useful for exploring the design space early in the design cycle and gaining valuable understanding and intuition about the system performance. Sensitivity analyses and optimizations also change parameter values in multiple simulation iterations; typically these are used later in the design cycle for validation.

Vehicle Simulation Size Relative to WavelengthThe simulation of individual antenna structures and their far field radiation patterns has been a staple of EM simulation software for many years. This includes free-standing antennas as well as on-chip antennas closely connected to amplifiers in integrated circuits (ICs). More recently, with the advent of 64-bit computing and the increase in RAM that it makes available for individual simulations, EM simulation has expanded to include antennas and vehicles together; however, the vehicle might be represented in a different EM formulation that may only look at the surface metal of a car, satellite, ship, or airplane.

Figure 3 – Distribution of electric fields 1.8 ns after being launched.


Figure 4 – Parametric analysis is used to improve design performance.

Figure 5 – GPUs reduce simulation time for 4 GB and 20 GB problems.


The challenge to achieving high-accuracy simulation of antenna structures and vehicles together, using one fully arbitrary 3D EM simulation, has been the simulation problem size, often described in terms of the number of elements in the mesh or how much RAM (memory) the problem consumes. A simulation requiring too many GB of RAM becomes impractical either because it takes too many hours to run or because the simulation goes completely beyond the available computer hardware capability.

EM simulation of an antenna generally scales with signal frequency because the EM simulation accuracy is based largely on the number of mesh cells per wavelength. A half-wavelength dipole antenna simulation takes about the same amount of simulation time at low or high frequency because the mesh cell size scales to the antenna dimension based on wavelength. Simulation of an antenna mounted on a vehicle in one fully arbitrary 3D EM simulation includes both structures. Higher signal frequency means smaller wavelength and a smaller cell size is needed in order to accommodate the antenna. This smaller mesh means more mesh cells are utilized to simulate the portions of the car.

Mesh size can vary within one simulation, with larger mesh cells of 1.25 mm around large physical features like bumper assemblies and smaller mesh cells of 0.04 mm near finer geometries like the feeding structure of a sensor’s antenna, but there is always a limit to the range in mesh size that is practical or accurate for a single simulation. The ability to now simulate a high frequency radar device and antenna along with the bumper area of a car in one fully arbitrary 3D EM simulation is a benefit of the FDTD method of EM simulation. FDTD provides both the ability to scale mesh size linearly with problem size and to leverage tremendous efficiencies with CUDA-enabled GPU systems.

FDTD Simulation Scales Linearly with Problem SizeIn the world of fully arbitrary 3D EM simulation, there are frequency domain and time domain formulations. Although both types can simulate steady state frequency domain data, including S-parameters, there are differences in how quickly the simulation time grows as the simulation problem size grows. There are frequency domain EM simulation formulations where the simulation time grows at a rate of n-squared, where n is the problem size. One of the advantages of FDTD simulation for large problem sizes is that time domain simulation execution time grows only linearly as the simulation problem size grows1. The larger the problem size, the greater the relative benefit of time domain simulation versus frequency domain simulation.

Time domain simulators run an entire simulation for each port in a design. Generally frequency domain simulators don’t need to do this. For some simulations with many ports, a frequency domain EM formulation, such as finite element method (FEM), may be a good choice. For an antenna application that does not

involve many signal ports in a design, time domain simulation has the advantage for large problem sizes.

FDTD Parallelizes Well with GPUsA popular approach to simulating large EM structures quickly utilizes CUDA-enabled GPUs. CUDA, the Compute Unified Device Architecture, is a parallel computing platform created by NVIDIA and implemented by the graphics processing units (GPUs) that they produce. Originally developed for accelerating video graphics, GPUs are popular for many high performance computing (HPC) applications.

The comparison between GPU and traditional CPU computing is dramatic. GPUs can apply hundreds of processors where CPUs can only offer a few. More than frequency domain EM simulation, time domain EM simulation parallelizes well; FDTD can take full advantage of the simulation time acceleration offered by GPUs.

SummaryDesigning an automotive radar sensor is a challenging task even before introducing the complexities of mounting brackets and bumper assemblies. Computational FDTD EM simulation offers the tools necessary for engineers to perform a high fidelity analysis of the sensor while considering final mounting configurations. This is enabled by XFdtd’s XStream® GPU Acceleration technology that tremendously reduces EM simulation time by leveraging GPUs and enabling XF to make ultra-fast FDTD numerical computations. In the end, engineers can move the automotive safety industry forward by increasing the reliability and accuracy of radar systems.

[1] Microwave Circuit Modeling Using Electromagnetic Field Simulation by Daniel G. Swanson, Jr. and Wolfgang J. R. Hoefer, Artech House c 2003 ISBN: 1-58053-308-6

NVIDIA and CUDA are trademarks and/or registered trademarks of NVIDIA Corporation in the United States and other countries.

Remcom provides innovative electromagnetic simulation software and EM consulting services.

Their products simplify the analysis of complex EM problems and lead the market in FDTD-based modelling and simulation.

Cell phone antenna design, MRI coil analysis, antenna placement on vehicles and airplanes, and placement of wireless communication systems are made easier with Remcom’s EM simulation software and electromagnetic modelling expertise.

For more information on the software products available from Remcom please contact AR UK Ltd

Tel: 01908 282766 Email: [email protected] Web: www.arukltd.co.uk


This article, and the ones that will follow it, are about dealing with EMC issues during design and other project stages, to save time and money; reduce project/financial risks, and to help ensure that if we take products to a ‘proper’ EMC test lab for compliance testing, they will pass on the first test.

(It is important to note that for CE marking for legal sales in the European Union, there is no legal requirement under the EMC Directive to have ever done any EMC testing, which is a big help to start-up companies. Many established companies use EMC laboratory testing to help demonstrate that their products comply, but it is important to note that a product can pass all of the relevant EMC test standards and yet cause or suffer EMI in real-life and so fail to comply with the Essential Requirements of the EMC Directive. Discussing these issues goes beyond the remit of this article, but I have often written about them in the past.)

Close-field EMC probing (often called near-field probing) is difficult to do accurately, but it is an excellent qualitative technique that can be used to compare the EM characteristics of one thing, with those of another.

For this reason, although – like computer simulation – close-field probing cannot (generally, yet) be used to prove that a particular EMC laboratory test would be passed, it is of huge benefit in helping us discover and fix EMC problems.

These EMC problems can arise in all stages in the life of a module, product, equipment, system or installation (which I’ll call an ‘item’ in the rest of this article) – from its initial proof-of-concept, through design, development, regulatory approval, Quality Assurance in serial manufacture, installation, etc. all the way to upgrades, repairs and refurbishments.

I think we all realise that the best time to deal with a risky design issue is as close to the start of a project as possible, when design changes cost little and there is plenty of design freedom. But many companies still guess at EMC design issues, leaving the discovery of EMC problems until near the end of a project when any changes are very costly and there is little design freedom.

It is a common joke that if you ask two EMC consultants the same question you will get three different answers – but one thing that all of the EMC consultants I have ever met agree on, is that time and cost will be saved overall by dealing with EMC design issues earlier in a project, compared with leaving them until the end.

The choice of materials for the construction of an item, and its mechanical design, is often done a long time before the electronic hardware is ready to be fitted into it, and this is often

some time before its software is ready and all of its functions can be tested.

When EMC problems are discovered at this late stage in a project, it is often the case that a different choice of mechanical materials and/or a different mechanical design would easily solve the problem – unfortunately these are issues that are pretty much ‘set in stone’ and difficult, costly and time-consuming to change.

Close-field EMC probing is low-cost and very useful, and for decades I (and many others) have been using them to detect the ‘leakages’ from electronic items to discover and fix the ‘weak spots’ that are probably causing the EMC test failures. For examples of this, see [1] [2] and [3].

These techniques can help to reduce the delays in time-to-market caused by the shortcomings in the EMC design, sometimes dramatically so. For example, it is not very unusual to find a problem and its solution in a few minutes, by using a close-field probe, when engineers working without the benefit of close-field probing have already spent several weeks and got nowhere. Once people learn to use close-field probes as described in these references, they wonder how they ever managed without them!

However, there are ways of using close-field probes to de-risk a range of EMC design issues very early in a project – long before the hardware or software are designed – when the mechanical design is being started and the constructional materials chosen.

I have read about these techniques from time to time, and promised myself I would investigate them, but you know how time flies...

Anyway, I was recently asked to present a full-day seminar on close-field probing techniques that save time and cost, and so I thought it was time that I finally got to grips with the kinds of techniques described by Scott Roleson [4] [5] [6], Doug Smith [7], Dr. Arturo Mediano [8], Ken Wyatt [9], by Tim Williams in the EMC Training Programmes held at EMC-UK events over recent years [10], and anecdotally by many others.

The material that I have gathered as a result will take more than one article in the EMC Journal to describe, so this article is mostly an introduction.

We can easily make close-field probes, even from a paper clip, see Figures 1, 2, 3 and 4. The largest probe dimension (i.e. the diagonal or major diameter of a loop) should be less than 1/6th of the wavelength at the highest frequency to be measured (e.g. for < 1GHz: < 50mm diameter) so that – even when placed close to a large lump of dielectric such as a PCB – they

Usingclose-fieldprobestoreducedesignrisksearlyinaprojectBy Keith Armstrong (www.cherryclough.com)


are still ‘electrically small’ and well below their frequency of first resonance.

Figure 1 – The construction of a good-quality close-field magnetic probe.

Figure 2 – An easier magnetic field close-field probe design (but not so good).

Figure 3 – The simplest magnetic close-field probe design (but even less good).

Figure 4 – Using a paper clip to make an unshielded close-field probe.

Close-field probes are often hand-made from ‘microwave semi-rigid’ cable, e.g. RG402 (approx. 3mm outside diameter) or RG405 (approx. 2mm outside diameter) because the stiffness of this type of cable helps the probes to retain their shape and so give more repeatable results, and also because their solid copper shields are very effective indeed.

An additional benefit is that the dielectric material in these semi-rigid cable types is solid Teflon, and so is unaffected by soldering at any normal temperatures. SMA connectors (male and female types) are readily available for soldering directly to these same cable types, helping to make robust and reliable probe assemblies.

Magnetic-field close-field probes are often called ‘loop’ probes, but there is no good reason for making them in a circular shape. In fact, rectangular probes have some advantages when used on flat surfaces, as is often the case in practice. And, I have recently discovered that making them rectangular is much easier and quicker than trying to bend semi-rigid cable into a neat circle!

I don’t plan to discuss electric-field close-field probes in this article, because as yet I have no real experience with them. But I often use unshielded loop probes (like the paper clip probe in Figure 4) when searching for ‘leakages’ and ‘weak spots’, because they pick up electric (E) fields as well as magnetic (H) fields. When we don’t know the nature of a possible leakage (i.e. whether it leaks E or H fields) using an unshielded loop probe can help save time in locating it.

Figure 5 shows four probes that are simply made of enamelled copper wire soldered to SMA PCB-mount connectors: unshielded loop probes that I really ought to insulate better (so I never let anyone else use them).


Figure 5 – The range of close-field probes that I use (at the time of writing).

When we don’t feel like spending the time making our own close-field probes, or when a professional appearance matters, we can purchase close-field probes from numerous suppliers of EMC test equipment, for example those in Figures 6, 7, 8 and 9.

Figure 6 – Examples of close-field probes from Aariona, Laplace Instruments and ETS-Lindgren.

Figure 7 – Some of the many close-field probe kits from Langer EMV-Technik.

Figure 8 – Hewlett-Packard’s venerable close-field probes, and currently available ones from Agilent (soon to be renamed Keysight Technologies) and Teseq (which used to be Chase EMC).

Figure 9 – Examples of close-field probes from Hameg and Com-Power.

Close-field probes can be used to great effect with spectrum analysers costing as little as £800, such as those in Figures 10 and 11. These are all portable instruments, but some require mains power whilst others can run on their built-in batteries – very handy for discovering problems in the field.

Figure 10 – Examples of portable spectrum analysers, including some very low-cost ones.


Figure 11 – Some more examples of portable and low-cost spectrum analysers.

It is also possible to use close-field probes with oscilloscopes that we probably already have, although we would have to learn to view and understand the resulting waveforms instead of spectra. Some oscilloscopes have FFT capabilities, but I have rarely found the spectra they produce to compare with the same probe measuring the same thing using a spectrum analyser. However, I recently learned that Tektronix are now offering oscilloscopes with built-in ‘time domain’ spectrum analysers that are compliant (or nearly so) with CISPR 16 requirements and of course are much faster than the traditional swept-narrowband filter type of spectrum analyser.

To repeat the excellent work of Roleson, Smith, Mediano, Wyatt and Williams and use close-field probing to discover and solve EMC design issues before there is any hardware that can be operated to check for leakages, requires either a broad-band noise source or a spectrum analyser with a tracking generator.

A wide-range of broad-band noise sources are available from various suppliers, with useable upper frequencies from 1GHz to 40GHz. They may be called Comparison Noise Emitters (CNEs); Reference Noise Generators (RNGs); Emissions Reference Sources (ERSs); Comb Generators, etc., and there is even a rather lovely Universal Spherical Dipole Source (USDS).

Having searched on and off for an affordable spectrum analyser with a tracking generator for over a decade (my preference running to second-hand Agilent E7400s from eBay) I finally purchased a Rigol DSA 815 for a little over £1000. This is a Chinese brand, with a very high quality presentation and a user interface that – up to a point – is almost identical to the E7400 series (and even its predecessor, the HP8591E series – the ‘green screen’ portable workhorse of the EMC industry for many years).

Ken Wyatt had reviewed the very same model in 2012, [11], and been very impressed with its price/performance ratio. He also used it in [9].

Trying to repeat the work described in references [4] through [9], I found that my usual quick-to-make low-cost H-field probe construction method (Figure 3) gave very variable results in some sensitive types of measurements. I think it

must be that because they were not very well balanced, they were very susceptible to hand-capacitance and even just the proximity of metal and dielectric objects (or bodies).

By trial and error I found that adding about 200mm of ferrite tubes gave much better, more repeatable performance, allowing me to use my quick and easy-to-make close-field probes. Figure 12 shows two such probes under construction, with their strings of ferrite tubes exposed.

Figure 12 – A view of my new probes during assembly.

Because EMI-suppressing ferrite materials are conductive to some degree, I wanted to prevent variations in contact resistance from occurring between the tubes and the copper shield. I also wanted to reduce hand-capacitance effects as much as I could. So before feeding the tubes onto the probes, I first covered the copper semi-rigid cables’ shields with heat-shrink insulating sleeve (just visible (yellow) at either end of the strings of ferrites in Figure 12).

I don’t know if this precaution was worthwhile, but it seemed like a good thing to do.

Then I ransacked the various ferrite sample kits I had been given over the last 24 years to find ferrite tubes that had inner diameters just large enough to slip over the heat-shrink sleeving. As Figure 12 shows, they were mainly from Wurth, Kitagawa and Steward (which is now owned by Laird Technologies). I don’t think the type of ferrites used matters a great deal, as long as they have their highest impedances generally around the middle of the frequency range of interest for close-field probing – in my case between 50 and 1000MHz.

To get a good fit to the heat-shrunk semi-rigid cable, the SMA connector should only be soldered to the semi-rigid after the ferrites have been assembled onto the probe.

With at least a 200mm length of ferrite tubes slid onto the ‘handle’ of the probe, I then heat-shrunk over the top of them all, to stop them from moving around and possibly affecting performance. Also, the shrink sleeving might help to reduce hand-capacitance effects, and will certainly help to protect the ferrites from damage – they are very brittle and can easily become cracked by rough handling or accidents.


Figure 13 – My new RG405 probes when finally assembled.

The2-probemethodoffindingflawsinshieldingThe first close-field probing technique I want to describe uses two probes, one energised by the spectrum analyser’s RF output from its tracking generator, the other connected to its RF input, as shown in Figure 14.

The metal box being used is my ‘famous demo box’ – created over a weekend using hand tools (and it shows) for a bit of entertainment during a break in an EMC conference in 1992. It – and much prettier, professionally-made versions of it – have since been used to give hundreds of EMC demonstrations worldwide.

(My demo box is intentionally unpainted and free from other surface treatments, because its aluminium-zinc casting alloy maintains a low contact resistance (unlike plain aluminium) which is important for making good connections to conductive gaskets and also for various things that I use it to demonstrate. It looks rather ugly, but my professionally-made versions had nice shiny mirror surfaces, achieved by a technique similar to French-polishing.)

My demo box is based on having a noisy circuit inside, plus connectors for power and data cables, to be close-field probed in the traditional way of looking for leakages, as a means of demonstrating good practices in enclosure shielding, cable shielding, and filtering.

But here I am using it without any power to its internal circuits, to see how much of what I know about its EMC design issues can be discovered by using a spectrum analyser (SA) with a tracking generator (TG) and two close-field (CF) probes. To see if such EMC design flaws could be reliably detected during the early stages of an item’s mechanical design, when design freedom is high and design changes cost little.

In Figure 14 I am holding the two CF probes – one connected to the TG’s RF Output, the other to the SA’s RF input – close against the solid metal of the demo box’s lid. Figure 15 shows the result on the SA’s screen: the measure of the RF energy that couples between the two probes.

Figure 14 – Looking for shield imperfections with two CF probes – the set-up (1).

Figure 15’s amplitude is scaled at 10dB/decade, the internal pre-amplifier is switched on to reduce the noise floor, the RF attenuator is set (manually) to 0dB and the top of the amplitude scale is -20dBm (although the units don’t matter, only the dBs, because we are making comparisons: relative measurements, not absolute ones).

The horizontal axis displays the frequency range from 10MHz to 1GHz, on a linear scale. The resolution bandwidth (RBW) is 120kHz, the video bandwidth (VBW) is 300kHz, and the TG’s output level is set to -10dBm so as not to overload the RF input when we get to Figures 20 and 21.

(I suppose I could have set the RF attenuator to -10dB and the TG to 0dBm, but I am used to setting the RF attenuator to 0dB to maximise sensitivity when using CF probes to measure leakages with low-cost SAs, so it has become a habit.)

Figure 15 – Looking for shield imperfections with two CF probes – the display (1).

Figure 15 shows that the coupling between the two probes is about -80 to -90dBm between 10MHz and 700MHz (i.e. an attenuation of -60 to -70 dB, given that the Reference Level is -20dBm), with a slight rise to -75dBm to -80dBm (i.e. -55 to -60dB) around 1GHz.

The ripples that can be seen on the display are most probably due to the reflections caused by the impedance mismatches


inherent in my probe design – which puts a short-circuit at the end of a coaxial 50W transmission line. The ripples are not important for this kind of measurement, so I don’t mind them.

Figure 16 shows the two probes in the same physical relationship to each other and the lid of the metal box, but now slid forward to lie over the row of small holes, which has the same open area for ventilation as the larger slot we will come to in Figures 20 and 21.


Figure 17 shows almost exactly the same poor coupling between the probes as for set-up (1) in Figure 15.


Figure 18 shows the probes, still held in the physical relationship to each other and the lid of the metal box, but now slid even further forward to lie over the solid metal inbetween the row of small holes and the larger slot. Figure 19 shows almost exactly the same poor coupling between the probes as for set-up (1) in Figure 15 and set-up (2) in Figure 17.



Figure 20 shows the probes, as previously in the same physical relationship to each other and the lid of the metal box, but now slid further forward to lie over the large slot. Figure 21 shows markedly higher coupling between the probes than we saw with set-ups (1), (2) or (3) (Figures 15, 17 or 19 respectively).




Figure 21 shows that over most of the frequency range, the receive probe is now picking up around -45 to -55 dBm (i.e. an attenuation of -25 to -35dB), rising above about 700MHz to around -35dBm (i.e. -15dB attenuation) at 1GHz.

To see if this roughly 35dB increase in coupling (decrease in attenuation) between the two CF probes is caused by the slot rather than the close proximity of the edge of the box lid, set-up (5) is shown in Figure 22 and its results in Figure 23.



Figure 23 shows that the coupling between the CF probes is once again as low as it was for set-ups (1), (2) and (3).

Clearly, the large slot allows RF energy in the range 50MHz to over 1GHz to couple much more strongly between the two CF probes, than the other structures on the lid of the box. We might expect this to indicate that we should expect much less shielding effectiveness from the slot, than from the row of holes having the same ventilation aperture, and indeed this is what we see when probing the powered-up box for its RF leakages in its traditional ‘demo’ role.

So there we have it – a mechanical EMC design flaw revealed very early in a project well before there was any hardware or software that could make it possible to test the item in a laboratory to any of the relevant published standards for EMC compliance, such as CISPR 22 or 24 (EN 55022 or EN 55024).

And I haven’t mentioned it so far, but a very important and useful feature of most CF probing techniques is that they can be done almost anywhere, anytime, on our desks or assembly/test benches, and certainly don’t need a shielded room!

If our neighbour happens to be operating a very noisy prototype in close proximity, we may need to wait until he or she stops, or move a metre or two to quieter location, and it may also prove necessary in some situations to load all the mains or other cables to our desk or test bench (not just the power cable to the SA, but all of them) with clip-on ferrite tubes. But in many cases such measures are not needed.

Those who need high-performance shielding, and/or to shield frequencies much higher than 1GHz, will of course find that the row of holes in set-up (2) (Figure 16) has too little shielding effectiveness (although not anything like as bad as the large slot).

If high-performance shielding is required, there are a number of improvements to this two-probe method that should help (although I haven’t tried them myself yet):

• Increase the TG’s output level.

• Use an external RF power amplifier if necessary, but in this case feed its RF output to the energised probe through a 50W 6dB attenuator of the same or higher power rating as the amplifier, so as not to provide the amplifier with so much of an impedance mismatch that it could be damaged.

• Vary the physical relationships between the two probes, and between the probes and the metal surface, to see if greater sensitivity can be achieved.

• Try using probes with larger loop areas.

• Use a more expensive SA with a larger dynamic range (i.e. a lower noise floor).

• Use a narrower RBW to improve the dynamic range.

• Use trace averaging to help improve the dynamic range (only useful when the noise floor, when the two probes are both over solid metal, looks like random noise).

• Use high-performance double-screened RF coaxial cables from the SA to the probes, load the cables with clip-on


ferrites, keep the RF Output cable far away from the RF Input cable.

Alternatively, the ‘internal RF excitation’ method shown in Figures 35 through 40 in this article might prove to be more suitable.

Continuing with the 2-probe method of detecting flaws in shielding, the lid of my ‘famous’ demo box is fitted to its base with a conductive gasket clamped between them – except where part of the gasket is missing along one long edge.

Figure 24 shows the 2-probe method applied to a lid-to-base joint where we know the conductive gasket is present (it is written on the box!). Let’s call this set-up (6). Figure 25 once again shows poor coupling between the two probes (just as we had for set-ups (1), (2), (3) and (5) above).

Figure 24 – Looking for gasketting imperfections with two CF probes – the set-up (6).

Figure 25 – Looking for gasketting imperfections with two CF probes – the display (6).

But when the probes are applied to the side with the missing gasket, as shown in Figures 26 and 27, we quickly see that the coupling between them has increased by 20 to 30dB.

Figure 26 – Looking for gasketting imperfections with two CF probes – the set-up (7).

Figure 27 – Looking for gasketting imperfections with two CF probes – the display (7).

As well as being able to be used for checking adequate gasket design at an early stage in a project, this technique could be used in serial manufacture to discover whether a gasket had been mis-assembled; and used when fault-finding in the field to discover if a gasket had become ineffective due to corrosion, in both cases being a quick diagnostic tool that does not require dismantling the item concerned to be able to look at the gasket (or where it should be).

The1-probe‘reflectometer’methodoffindingflawsin shieldingFigures 28 and 29 show one of my new ferrite-handled probes being used with a directional coupler, in this case a Mini-Circuits’ ZFDC-20-5+ with SMA connectors that match my CF probes and cables.

This little module cost me about £80, and is specified to have nominally -19.5dB of directional coupling from 100kHz to 2GHz. I am using it backwards as a reflectometer – as Figure 29 shows.


Figure 28 – Looking for shielding imperfections with a reflectometer – normalising.

Figure 29 – A closer view of the directional coupler in Figure 28.

Used in this way, any RF that is not reflected at the impedance mismatch caused by the ‘shorted-turn’ CF probe will be revealed as a dip in the response, but – as Tim Williams of Elmac Services warned me – the 20dB or so loss in the directional coupler makes this a relatively insensitive method. So as can be seen in Figures 30 and 32, I have set the vertical axis to 1dB per division. All the other SA and TG settings are the same as for the two-probe method described earlier.

With this method, the first step is to ‘normalise’ the measurement with the probe held against a solid piece of metal, as shown in Figure 28. Figure 30 shows the resulting display – a straight line along the 0dB line at the top of the display.

Figure 30 – Looking for shielding imperfections with a reflectometer – the normalised display.

Figure 31 shows set-up (8), with the normalised probe moved to the large slot on the top of the box, without changing its proximity to the box’s metal surface (it is always held against it, touching the metal surface).

Figure 31 – Looking for shielding imperfections with a reflectometer – set-up (8).

Figure 32 – Looking for shielding imperfections with a reflectometer – the display (8).

Figure 32 shows the resulting display, when the CF probe has been moved around so as to maximise the depth of the dip, which is caused by energy being lost into the shield imperfection (instead of being 100% reflected back into the probe as perfect shielding would do).

The maximum dip depth is reached with the probe at one end of the slot, which is not unexpected because it is the location of the maximum magnetic field emissions from an ‘accidental slot antenna’ at resonance.

The dip frequency correlates well with the first resonance frequency at 643MHz (i.e. when the slot’s length equals half a cycle of the wavelength).

This is different from the two-probe method described earlier, which did not reveal anything about the slot’s resonant frequencies. I think this is because the two-probe method simply measures the coupling between the fairly localised eddy current patterns for the probes, which do not extend far enough to excite the whole length of the slot and cause it to resonate.


Quite probably, if when using the two-probe method, we located one probe at each end of the slot, the slot’s first resonance frequency would then show up.

Figure 33 shows the reflectometer method being used to identify the missing gasket on my demo box, with Figure 34 its displayed output.

Figure 33 – Looking for shielding imperfections with a reflectometer – set-up (9).

Figure 34 – Looking for shielding imperfections with a reflectometer – the display (9).

The dip in Figure 34 is only about 2.5dB, but it is at exactly the same frequency as the dip measured for the large slot in set-up (8) – Figure 31. This was not unexpected, because the demo box’s missing length of gasket is exactly the same as the length of the slot in its lid – so they will have the same first resonance frequency.

So not only does this method identify the fact that there is a missing (or badly degraded) gasket, it finds its ends and makes it possible to determine how much length is missing (again, without dismantling the item).

The 2-probe ‘internal illumination’ methodFigure 35 shows one of my more basic CF probes (no ferrites on its handle) probing the row of small holes on the lid of my demo box, while the TG’s RF Output is fed directly to a CF probe that is inside the demo box.

Figure 36 shows the location of the CF probe, which is nothing more than a 95mm-long piece of (insulated) wire sticking into the box via a ‘through-bulkhead-mounting’ SMA connector.

This is an E-field CF probe, being used here to ‘illuminate’ the inside of the box with RF energy from the TG.

Figure 35 – Looking for shielding imperfections with internal illumination – set-up (10).

Figure 36 – Looking for shielding imperfections with internal illumination – the internal CF probe.

Figure 35 shows the capture of a yellow trace whilst the probe is held away from the long slot, and Figure 37 shows that yellow trace (Trace 1) ‘frozen’ while the pink trace (Trace 2) is updated with the probe now moved over the long slot.


Figure 38 shows the resulting display. The yellow trace is for the CF probe on the box lid but away from the large slot, while the pink trace shows the same probe, held in the same way, but moved to the middle of the large slot.


Figure 38 – Looking for shielding imperfections with internal illumination – displaying both (10) and (11).

Clearly, the moveable CF probe was picking some emissions from the fixed E-field probe inside the box when it was not over the large slot, set-up (10), but also clearly it was picking up significantly more emissions when it was over the slot, set-up (11). Figures 39 and 40 show exactly the same procedure using one of my newer ‘ferrite handled’ probes (although set-up (12) for the yellow trace was not photographed).

These photographs show that – for this kind of CF probe test at least – the ordinary probes do just as well as the ones with 200mm of ferrite tubes on their handles.


Figure 40 – Looking for shielding imperfections with internal illumination – displaying both (12) and (13).

I have a lot more material on these sorts of CF tests, which can be done by (or for) mechanical designers early in a project to de-risk the choice of materials, assembly methods and overall design – but I have run out of room, so they will have to wait for future editions of the EMC Journal.

References[1] “EMC Testing”, by Tim Williams and Keith Armstrong,

EMC Compliance Journal, 2001-2002, available from www.cherryclough.com and www.theemcjournal.com. This is a series with 7 parts, and only Parts 1 and 2 are especially relevant to close-field probing.

[2] “Signal and Noise Measurement Techniques Using Magnetic Field Probes”, by Doug Smith, IEEE 1999 International EMC Symposium, reprinted at http://emcesd.com/pdf/emc99-w.pdf.

[3] “Cost-effective use of close-field probing” webinars parts I and II, by Keith Armstrong, may be viewed at www.interferencetechnology.com/webinar-series (scroll down the webpage).

[4] “Evaluate EMI Reduction Schemes with Shielded-Loop Antennas”, Roleson S, EDN, 29(10):203—207, 1984, which does not seem to be available via Google.

[5] “Benchtop EMC Testing Techniques for Medical Equipment (using close-field probes)”, Scott Roleson, Medical Device & Diagnostic Industry Magazine, January 1998, available from www.mddionline.com/article/benchtop-emc-testing-techniques-medical-equipment.

[6] “Finding EMI Resonances in Structures”, Roleson S, EMC Test Design, 3(1):25—28, 1992, which also does not seem to be available via Google.

[7] “Measuring Structural Resonances”, by Doug Smith, ‘Technical Tidbit, June 2006’, available from www.emcesd.com/tt2006/tt060306.htm. There is a great deal more on close-field probing, other useful diagnostic techniques and much else on EMC and especially ESD at Doug’s website: www.emcesd.com. A quote from a visitor to this site: “Every time I browse your site, I never get any work done. I spend hours on it and get in trouble.” – so don’t complain that you were not warned!

[8] “Near field probes: Useful tools for Electronic Engineers”, Dr. Arturo Mediano, EMC-Europe 2013, Bruges, 2-6 Sept, Short Course 1.

[9] “Measuring Resonance in Cables”, Ken Wyatt, EDN, October 29, 2013, www.edn.com/electronics-blogs/the-emc-blog/4423597/Measuring-resonance-in-cables.

[10] For example, EMC-UK 2014: www.emcuk.co.uk/conference, but please note that this year’s EMC-UK training programme might not cover close-field probing techniques as it often has in previous years.

[11] “First impressions - Rigol DSA815TG spectrum analyser” by Kenneth Wyatt, in EDN, July 06, 2012, www.edn.com/electronics-blogs/the-emc-blog/4389791/First-Impressions--Rigol-DSA815TG-Spectrum-Analyzer.


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Issue 112 June 2014 - nutwooduk.co.uk