USCEL Third RunEMI Round Robin

Roland Gubisch

Intertek

Third Run

• Program goals

• third run history

• results

Third run

• Program goals

– Provide interlaboratory EMI comparison opportunity to meet accreditation requirements

– Explore the 1 – 18 GHz range, increasingly popular owing to RFID and WLAN devices

Third run history

1) Low-cost test object ordered October 2003.

2) Test object sent to NWEMC and CCS for preliminary evaluation December 2003.

3) Test object found to have low radiated output, no conducted capability. Returned to vendor April 16, 2004.

4) Alternate test object sent to CCS for evaluation June 8, 2004. Found to be OK.

5) Alternate test object circulated to participants starting July, 2004.

6) Last testing November 1, 2004. All data submitted to ACIL by November 30, 2004.

6) Round Robin report issued to participants December 8, 2004.

Third run test object

Third run results

• No reference calibration; results are compared to group average.

• Data includes lab measurements of:

– direct conducted emissions– 3m vertical and horizontal radiated, average

and peak detector.

Third run results

In the charts that follow, please note that thevertical scales are identical for each type oftest:

± 8 dB for direct conducted

± 25 dB for radiated

Direct conducted 1 – 18 GHz (all labs)

direct conducted emissions - deviation from average

-8

-6

-4

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0 5 10 15 20frequency, GHz

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, dB

Lab 1

Lab 2

Lab 3

Lab 4

Lab 5

Lab 6

Lab 7

Lab 8

Lab 9

Lab 10

Lab 11

Lab 12

Lab 13

Direct conducted 1 – 18 GHz (no outlyers)

direct conducted emissions - deviation from average

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-6

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0 5 10 15 20frequency, GHz

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Lab 1

Lab 2

Lab 5

Lab 7

Lab 8

Lab 9

Lab 10

Lab 11

Lab 13

Direct conducted 1 – 18 GHz

OBSERVATIONS: 1. Neglecting outlyers, the deviations of individual measurements from average result lies within 4 dB. The majority of measurements lie within 2 dB of the average.  2. For the range 0.15 - 30 MHz tested in the 2003 Round Robin, the average direct conducted results fell within 3 dB and the majority were within 2 dB. 3. Thus there is a somewhat larger dispersion of direct conducted measurement results in the range of frequencies above 1 GHz. This is likely to arise from higher - and possibly unaccounted - cable and connector losses at the higher frequencies, cable/connector impedance mismatch, and larger measuring instrument uncertainty.

Direct conducted 1 – 18 GHz

adapter attenuation, dB

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0.5

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frequency, GHz

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3m horizontal, average detector (all labs)

radiated 3m H average - deviation from average

-25-20-15-10-505

10152025

0 5 10 15 20frequency, GHz

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, dB

Lab 1

Lab 2

Lab 3

Lab 4

Lab 5

Lab 6

Lab 7

Lab 8

Lab 9

Lab 10

Lab 11

Lab 12

Lab 13

3m horizontal, average detector (no outlyers)

radiated 3m H average - deviation from average

-25-20-15-10-505

10152025

0 5 10 15 20frequency, GHz

dev

iati

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, dB

Lab 1

Lab 2

Lab 4

Lab 7

Lab 8

Lab 9

Lab 10

Lab 12

Lab 13

3m horizontal, average detector

OBSERVATIONS: 1. Neglecting outlyers, the deviations of individual measurements from average result increase from about 5 dB at the lowest frequencies tested here to 10 dB at 18 GHz.  2. For the range 30 - 1000 MHz tested in the 2003 Round robin, the average 3m radiated results fell within 20 dB at 30 MHz to 5 dB at 1 GHz. 1. Thus the highest deviations from average have occurred in the 2003 and 2004 Round Robin tests at the extreme ends of the radiated measurement spectrum – below 60 MHz and above 10 GHz. In between, variations have been generally within 5 dB. .

3m horizontal, peak detector (all labs)

radiated 3m H peak - deviation from average

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10152025

0 5 10 15 20frequency, GHz

dev

iati

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, dB

Lab 1

Lab 2

Lab 3

Lab 4

Lab 5

Lab 6

Lab 7

Lab 8

Lab 9

Lab 10

Lab 11

Lab 12

Lab 13

3m horizontal, peak detector (no outlyers)

radiated 3m H peak - deviation from average

-25-20-15-10-505

10152025

0 5 10 15 20frequency, GHz

dev

iati

on

, dB

Lab 1

Lab 2

Lab 4

Lab 5

Lab 7

Lab 8

Lab 10

Lab 12

Lab 13

3m horizontal, peak detector

OBSERVATIONS: 

•Peak and average results are very similar, with somewhat greater scatter overall in the peak measurements, and a

slight increase in scatter as frequency increases.

3m vertical, average detector (all labs)

radiated 3m V average - deviation from average

-25-20-15-10-505

10152025

0 5 10 15 20frequency, GHz

dev

iati

on

, dB

Lab 1

Lab 2

Lab 3

Lab 4

Lab 5

Lab 6

Lab 7

Lab 8

Lab 9

Lab 10

Lab 11

Lab 12

Lab 13

3m vertical, average detector (no outlyers)

radiated 3m V average - deviation from average

-25-20-15-10-505

10152025

0 5 10 15 20frequency, GHz

dev

iati

on

, dB

Lab 1

Lab 2

Lab 4

Lab 5

Lab 7

Lab 8

Lab 10

Lab 11

Lab 12

Lab 13

3m vertical, average detector

OBSERVATIONS:

• There is little significant difference between the data sets from vertical and horizontal polarization. Neglecting outlyers, the deviations of individual measurements from average result increase from about 5 dB at the lowest frequencies tested here to 10 dB at 18

GHz.

2. Outlying measurements show a larger deviation for vertical polarization at the highest frequencies than for horizontal. Peak and average results are very similar.

 3. Higher dispersion of measurement results at the higher frequencies is likely to arise from

higher - and possibly unaccounted - cable and connector losses at the higher frequencies, cable/connector impedance mismatch, and larger antenna calibration and measuring instrument uncertainties

 

3m vertical, peak detector (all labs)

radiated 3m V peak - deviation from average

-25-20-15-10-505

10152025

0 5 10 15 20frequency, GHz

dev

iati

on

, dB

Lab 1

Lab 2

Lab 3

Lab 4

Lab 5

Lab 6

Lab 7

Lab 8

Lab 9

Lab 10

Lab 11

Lab 12

Lab 13

3m vertical, peak detector (no outlyers)

radiated 3m V peak - deviation from average

-25-20-15-10-505

10152025

0 5 10 15 20frequency, GHz

dev

iati

on

, dB

Lab 1

Lab 2

Lab 4

Lab 5

Lab 7

Lab 8

Lab 10

Lab 11

Lab 12

Lab 13

3m vertical, peak detector

OBSERVATIONS: Dispersion of measurements increases with higher frequencies for all labs, but to a much lesser extent among the set from which outlyers have been removed. This suggests that some labs account more successfully than othersfor measurement factors that may not be significant at lower frequencies. Suchfactors might be:

•cable and connector losses •cable/connector impedance mismatch•larger antenna calibration and measuring instrument uncertainties•Support table reflections (low-density plastic is recommended)

Conclusions

• The best data is consistent with typical estimations of measurement uncertainty.

• Very large deviations exist at the high end of the measured range.

• There are good reasons for labs to sign up for Round 4.

What’s next?...

Poll among EMC Committee members, July 2003:

Test type % wanted

Radiated 1 – 18 GHz 45.8%

Telecom port conducted 20.8%

Disturbance power 16.7%

Radiated immunity 16.7%