AN INTRODUCTION TO

ELECTROMAGNETIC

COMPATIBILITY (EMC)PRESENTED BY

DR. WILLIAM G. DUFF

Applied Technology Institute 349 Berkshire Drive Riva, Maryland 21140 888-501-2100/410-956-8805 Website: www.ATIcourses.com Email: ATI@ATIcourses.com

ATI Course Schedule: http://www.ATIcourses.com/schedule.htm ATI’s Introduction To EMI : http://www.aticourses.com/sampler/Intro_to_EMI.pdf

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INTRODUCTION TO EMC DAY 1 SYLLABUS

Examples of EMI Elements of EMI Definition of Terms and Units Types of EMI Sources of EMI Propagation and Coupling Victims of EMI EMC in Wireless Systems

INTRODUCTION TO EMCDAY 2 SYLLABUS

EMI in Equipments and Systems EMI Coupling Modes Common Mode Coupling Differential Mode Coupling Common Impedance Ground Loop Grounding EMI Mitigation Filters, Ferrities, etc.

INTRODUCTION TO EMCDAY 3 SYLLABUS

Electromagnetic Shielding Shielding Applications Characteristics of Electromagnetic Fields Reflection Absorption Shielding Compromises Shielding Cables Design for EMC EMI Diagnostics and Fixes EMI Specifications and Standards

INTRODUCTION TO EMC DAY 1

Examples of EMI

What is EMI?

• RFI = Radio Frequency Interference

• TVI = Television Interference• Radio Noise• Electrical Noise• Transient Disturbances• Electromagnetic Pollution• Surges and Sags• Ground Bounce• Crosstalk• Corona and Arcing• Sparking• Electrostatic Discharges• Lightning Discharges

EMI = Electromagnetic Interference, Alias:• Relay Chatter• Noise Immunity Level• Audio Hum• Shot Noise• Flicker Noise• White Noise• Thermal Noise• Johnson Noise• TV Snow• Hum Bars• Motorboating• Degenerative Feedback• Hiss, Buzz and Hum• Screen Flicker

E3 = Electromagnetic Environmental Effects

EME = Electromagnetic EnvironmentEMC = Electromagnetic CompatibilityEMI = Electromagnetic InterferenceEMP = Electromagnetic PulseESD = Electrostatic DischargeHEMP = High Altitude EMP

HERF = Hazards of EM Radiation to FlightHERF = Hazards of EM Radiation to FuelHERO = Hazards of EM Radiation to OrdnanceHIRF = High Intensity Radiated FieldsHPM = High Power MicrowaveRADHAZ = Radiation HazardsRFI = Radio Frequency Interference

Historical EMI/E3-Related Incidents

Operation Restore Democracy (Haiti-1995)• Air wings of USS America & USS Eisenhower

replaced with men & helicopters of 10th Infantry Div. and 75th Ranger Regiment.

• Army aircraft not designed or tested for carrier operation, carriers required to turn off almost all communications and radar surveillance systems.

Pershing II Nuclear Missile (Germany)• Missile motor exploded during routine

maintenance• Electrostatic discharge identified as the

cause• 3 dead

Blackhawk Helicopter (Germany and USA - 1987)• Several potentially fatal incidents and a fatal crash• Suspected cause was interference from high

power radio transmitters• Entire fleet grounded for 3 months during

investigation• Extensive test and retrofit program necessary

USS Forrestal (Vietnam -1969)• ZUNI rocket inadvertently launched by a ship radar • 134 dead• 27 aircraft destroyed• $72M damage to ship ($335M in 2000 dollars)• Largest Naval loss of life since WW II

HMS Sheffield (Falkland Islands -1982)• Hit by undetected EXOCET missile• EMI caused degradation of surveillance

radar• 21 dead, • Ship sank 4 days later

Courtesy of Jose Reza

EMI CASE HISTORIES

• Blackhawk Helicopter• Aircraft Flight Controls• Automobile Electronics• Ship Propulsion System• Medical Electronics• Office Electronics• Consumer Electronics • Process Control

Proper Grounding and/or Shielding May Have Avoided May Have Avoided

Some of These ProblemsSome of These Problems

ELECTROMAGNETIC ENVIRONMENT EFFECTS (E3)

Performance degradation of receiver signal processing circuits

Erroneous or inadvertent operation of electromechanical equipments, electronic circuits, components, ordnance, etc.

Burnout or voltage breakdown of components, antennas, etc.

Unintentional denotation or ignition of electroexplosive devices, flammable materials, etc.

Personnel Injuries

ELECTROMAGNETIC ENVIRONMENT EFFECTS (E3) CONTINUED

POTENTIAL EMI INTERACTIONS

Interactions between on board equipments Interactions between on board equipments and

the electromagnetic environment Interactions between on board equipments and

test equipments

INTRODUCTION TO EMC DAY 1

Elements of EMI

ELEMENTS OF EMIELEMENTS OF EMI

SOURCESOF EMI COUPLING VICTIM OF

EMI

EMI CULPRIT AND VICTIMEMI CULPRIT AND VICTIM

EMISource

SignalSource

SignalReceiver

CULPRIT

VICTIM

COUPLING PATH

CONDUCTED OR RADIATEDCONDUCTED OR RADIATED COUPLING COUPLING

SOURCE COUPLING VICTIM

EMI SOURCES

TRANSMITTERSCOMPUTER CLOCKSELECTRIC MOTORS

SWITCHES AND RELAYSLIGHTNING

ELECTROSTATIC DISCHARGE

EMI COUPLING

CONDUCTED

Power Lines

Interconnecting Signal Cables

Common GroundImpedance

RADIATED

Antenna-to-AntennaCase Radiation

Case PenetrationField-to-WireWire-to-FieldWire-to-Wire

EMI VICTIMS

RECEIVERSANALOG SENSORS

ANALOG AMPLIFIERSCONTROL SYSTEMS

COMPUTERSORDNANCEPERSONNEL

PRIMARY EMI INTERACTIONSEMI SOURCE(EMITTER)

PRIMARY COUPLINGMECHANISM

EMI VICTIM(RECEPTOR)

RADIATEDANT-ANT

RECEIVERS

TRANSMITTERSRADIATED

ANT-CABLEANT-CASE

ELECTRONICEQUIPMENT

RADIATEDCABLE-ANTCASE-ANT

RECEIVERS

ELECTRICAL &ELECTRONICEQUIPMENT

RADIATEDCABLE-CABLECABLE-CASECASE-CABLECASE-CASE

CONDUCTEDPOWER LINESSIGNAL LINES

GROUND

ELECTRONICEQUIPMENT

EMI SOURCE(EMITTER)

PRIMARY COUPLINGMECHANISM

EMI VICTIM(RECEPTOR)

RADIATEDANT-ANT

RECEIVERS

TRANSMITTERSRADIATED

ANT-CABLEANT-CASE

ELECTRONICEQUIPMENT

RADIATEDCABLE-ANTCASE-ANT

RECEIVERS

ELECTRICAL &ELECTRONICEQUIPMENT

RADIATEDCABLE-CABLECABLE-CASECASE-CABLECASE-CASE

CONDUCTEDPOWER LINESSIGNAL LINES

GROUND

ELECTRONICEQUIPMENT

EXAMPLES OF ELECTRONIC-SYSTEM EMI

1. POWER CABLE EMISSIONS

2. POWER CABLE CONDUCTED SUSCEPTIBILITY

3. INTERCONNECTING CABLE CONDUCTED EMISSION

4. INTERCONNECTING CABLE SUSCEPTIBILITY

5. ANTENNA LEAD CONDUCTED EMISSION

6. ANTENNA LEAD CONDUCTED SUSCEPTIBILITY

EXAMPLES OF ELECTRONIC-SYSTEM EMI

7. COMMON GROUND IMPEDANCE EMISSION COUPLING

8. COMMON GROUND IMPEDANCE SUSCEPT. COUPLING

9. H-FIELD RADIATION

10. E-FIELD RADIATION

11. H-FIELD SUSCEPTIBILITY

12. E-FIELD SUSCEPTIBILITY

EMC ANALYSIS

Coupling

H();H(F)

InterferingTransmitter

SusceptibleReceiver

X(t)X(f)

y(t)Y(f)

Y(f) = H(f) Y(f)

LINEAR SYSTEMS

dτ τ)(tx )(τ h y(t)-

INTRODUCTION TO EMC DAY 1

Definition of Terms and Units

BASIC TERMS--POWER AND DB SCALE

2

110

122

1 10

1

2 10

2

1 10

1

210

22

11 10

2

110

VV log 20

ZZ when , ²

VVlog10

ZZ log10

²VVlog10

ZZ

²V2V1 log10

²/ZV²/ZVlog10

PPlog10dB

dB Power Voltage Ratio Ratio

dB Power Voltage Ratio Ratio

0 1.00 1.003 2.00 1.416 4.00 2.009 8.00 2.82

10 10 3.16 20 100 10 -10 .1 .300 -20 .01 .10

CIRCUIT AND FIELD RELATIONS

ELECTROMAGNETIC FIELDS

Time Varying Spatial Varying Electric Field Magnetic Field Velocity of Propagation Wavelength = C/ƒ (m) = 300

fMHz (ft) = 984

fMHz

ANTENNA FACTOR: RELATION BETWEEN ARRIVING FIELD STRENGTH, E, AND RECEIVER INDUCED VOLTAGE,

V.

INTRODUCTION TO EMC DAY 1

Types of EMI

NARROWBAND AND BROADBAND EMISSIONS

RECEIVER IMPULSE BANDWIDTH

t

ffc

BiVi/MHz

V=Vi/MHz • BiMHz

BiMHz= V 7dB C.W.B.W.Vi/MHz

BROADBAND EMI RELATIONSHIPS

V/MHz = V voltsBi (MHz)

20log V/MHz = 20log Volts- 20log Bi MHzdBV/MHz = dBV - BidB/MHz

EXAMPLES OF NARROWBAND EMI UNITS

Conducted

Radiated

PowerW

dBWdBm

VoltageV

dBVdBV

CurrentA

dBAdBA

Power DensityW/m2

dBW/m2

dBm/m2

Field StrengthV/m

dBv/mdBV/m

Magnetic Field (H)A/m

dBA/mdBA/m

Magnetic Flux Density (B)Tesla (Weber/m2)

Picotesla (pT)dBpT

EXAMPLES OF BROADBAND EMI UNITS

Conducted

Radiated

PowerdBm/kHz

VoltagedBV/MHz

CurrentdBA/MHz

Power DensitydBm/m2/kHz

Field StrengthdBV/m/MHz

Magnetic Field (H)dBA/m/MHz

Magnetic Flux Density (B)dBpT/MHz

FOURIER ANALYSIS

TIME DOMAIN(OSCILLOSCOPE VIEW)

Frequency Domain(Spectrum Analyzer,EMI Receiver View)

F

F0 = 1T

Sine Wave

TIME DOMAIN(OSCILLOSCOPE VIEW)

Frequency Domain(Spectrum Analyzer,EMI Receiver View)

TIME-FREQUENCY TRANSFORMATION OF PERIODIC FUNCTION

TIME-FREQUENCY TRANSFORMATION OF SINGLE PULSE

LIGHTNING, EMP, AND ELECTROSTATIC DISCHARGE

EMI IMPACT VISIBLE IN FREQUENCY DOMAIN