USCEL Third Run EMI 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 ) Test object sent to NWEMC and CCS for preliminary evaluation December ) Test object found to have low radiated output, no conducted capability. Returned to vendor April 16, ) Alternate test object sent to CCS for evaluation June 8, Found to be OK. 5) Alternate test object circulated to participants starting July, ) Last testing November 1, All data submitted to ACIL by November 30, ) 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 the vertical scales are identical for each type of test: ± 8 dB for direct conducted ± 25 dB for radiated

Direct conducted 1 – 18 GHz (all labs)

Direct conducted 1 – 18 GHz (no outlyers)

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 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

3m horizontal, average detector (all labs)

3m horizontal, average detector (no outlyers)

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 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)

3m horizontal, peak detector (no outlyers)

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)

3m vertical, average detector (no outlyers)

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)

3m vertical, peak detector (no outlyers)

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 others for measurement factors that may not be significant at lower frequencies. Such factors 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 GHz45.8% Telecom port conducted20.8% Disturbance power16.7% Radiated immunity16.7%