Conducted Immunity : Inconsistencies in power measurements

Discussion and questions regarding the Radiated Immunity and Conducted Immunity modules of RadiMation.
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Teabot
Posts: 2
Joined: 25 Jun 2024, 11:13

Conducted Immunity : Inconsistencies in power measurements

Post by Teabot »

I have an issue with the Conducted Immunity, specifically regarding my power measurements during test.

I have set up my test site with a CWS500N1, it has signal generator, amplifier and a power meter.
Test-Site1.png
Test-Site1.png (92.01 KiB) Viewed 25491 times
Test-Site2.png
Test-Site2.png (78.57 KiB) Viewed 25491 times


I have made a system calibration for this test. I am using a CDN (Luthi 801 M216) and have put a 150Ω on one side and a 100Ω on the other, going into the monitoring input of the CWS with a cable ending in a 40dB attenuator (protection for the internal power meter).

I have indeed set it up as a cable with a correction file for 40 dB in the test setup (I'm not including it as my screenshot is limited.)

Here is a handcrafted schematic.

Schematic_calibration.png
Schematic_calibration.png (31.95 KiB) Viewed 25491 times



Here is the set-up page.

Calibration_Forward.png
Calibration_Forward.png (93.38 KiB) Viewed 25491 times



Using this calibration I’ve tried testing using Substitution test and Multiband test and I’m finding different values in power for the same 10V test level. Real test using an EUT.
In addition, I’m finding different values when I set up the test using Signal Power calibration, when in my mind I should have the same values ?

Here are my tests setups:

multi-setting.png
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Substitution-setting.png
Substitution-setting.png (178.73 KiB) Viewed 25491 times


Set up for Forward power, Ive tried with Signal power
Here are tables from beginnings of tests:


Multiband using forward power || Substitution using forward power
Multi_Forward.png
Multi_Forward.png (167.01 KiB) Viewed 25491 times
Subs_Forward.png
Subs_Forward.png (162.87 KiB) Viewed 25491 times


Multiband using signal power || Substitution using signal power
Multi_Signal.png
Multi_Signal.png (178.14 KiB) Viewed 25491 times
Second test shows 32 dB on the CWS
Subs_Signal.png
Subs_Signal.png (146.55 KiB) Viewed 25491 times

Forward power on the CWS screen gives me 33 dB here


I am not sure how or where I’m going wrong here. I think I should have the same values regardless of basing the test on Signal or Forward power. 10V is the same level so…. ?

What am I missing here ?

Help would be greatly appreciated, thank you.
Last edited by Teabot on 26 Jun 2024, 12:10, edited 1 time in total.
Teabot
Posts: 2
Joined: 25 Jun 2024, 11:13

Re: Conducted Immunity : Inconsistencies in power measurements

Post by Teabot »

Here are my theoretical calculations :

From the values of my calibration at 30V I’ll need to substract 9.5 dB to get to 10 V values.
Table.png
Table.png (26.96 KiB) Viewed 25482 times

So it works for the side that I set up properly. When I set up Forward in my test the Forward power makes sense. Vice-versa for Signal.
However the other values change and do not correspond.
Is this normal ?
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