How can I perform magnetic field test for MIL-STD RS101

Discussion and questions regarding the Radiated Immunity and Conducted Immunity modules of RadiMation.
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incognito
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Joined: 03 Feb 2012, 13:07

How can I perform magnetic field test for MIL-STD RS101

Post by incognito »

How can I perform radiated emission magnetic field tests as described in MIL-STD RS101?
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joro
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Re: How can I perform magnetic field test for MIL-STD RS101

Post by joro »

The RS101 measurement as described by the MIL-STD, describes that a magnetic loop antenna should be used to generate a magnetic field in the frequency range of 30 Hz to 100 kHz. The current through the loop is a measure for the generated magnetic field, and this current can be measured using a shunt resistor, or a current sensor.
To get an accurate magnetic field it is necessary to calibrate the generated magnetic field by using another Field monitoring loop, which is connected a frequency selective powermeter.

The Magnetic field calibration can be performed in RadiMation by starting the Calibration > System Calibration > Radiated Immunity > Mil Std Calibration.
The 'Coupling Device' and the 'Measuring Device' allow to select the components that are used to measure the current through the magnetic field generation loop.
If as the 'Measuring device', the 'Power Meter' is selected, the device should be selected in the testsite as the 'Sensor powermeter'.
The magnetic field generation loop antenna (for example the ETS-Lindgren: Model 7605 ) should be selected in the testsite as the 'Antenna'.
The magnetic field monitoring antenna (for example the ETS-Lindgren: Model 7606) should be selected in the testsite as the 'Calibration antenna'. This antenna device driver should have a 'Magnetic Field Factor (dBpT/uV)' correction file selected as the third correction file in the device driver settings of the antenna device driver. ( also see: http://wiki.dare.nl/wiki/index.php/Chap ... correction )
The measurement receiver connected to the field monitoring antenna should be selected in the testsite as the 'Spectrum Analyzer'.

It is optional to also attach a 'Magnetic Flux Density' correction file as the second correction file in the device driver settings of the magnetic field generation loop antenna. The correction file should include a frequency column and a correction column, where the values in the correction column are expressed in 'pT/A'. (also see: http://wiki.dare.nl/wiki/index.php/Chap ... correction ). In the MIL-STD 462D, this correction value is specified as 9.5x10^7 pT/A. This 'Magnetic Flux Density' value is used to determine the calculated magnetic field based on the measurement of the current flowing through the magnetic field generation loop antenna.
TSF Configuration of the MIL-STD RS101 Calibration
TSF Configuration of the MIL-STD RS101 Calibration
MILSTDRS101Calibration.png (18.79 KiB) Viewed 10738 times
During the calibration for each frequency, the power level is regulated to the desired magnetic field level as it is measured by the 'Spectrum Analyzer' and the 'Calibration antenna'. When the calibration is performed and finished, the calibration results can be stored to a .CAL file.

To perform the real RS101 test, the earlier created calibration file can be used to generate the requested magnetic field.
Just use a Radiated Immunity Multiband test, and add a 'Magnetic Field substitution method testlevel' to the configuration. In the 'Magnetic Field substitution method testlevel' configuration the .CAL file can be selected again, and the requested testlevel can be specified. In this configuration dialog, also the levelling method can be selected, which also has the option to regulate on the current flowing through the magnetic field generation loop.
Example of the MIL-STD RS101 Test configuration TSF
Example of the MIL-STD RS101 Test configuration TSF
MILSTDRS101_MB_Immunity_Configuration.png (63.25 KiB) Viewed 10738 times
When this test is started, the current flowing through the loop antenna will be regulated to the current that is determined during the calibration, which correlates to the requested magnetic field.
heutink
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Joined: 22 Sep 2016, 11:23

Re: How can I perform magnetic field test for MIL-STD RS101

Post by heutink »

The above mentioned process is very time-intensive way of calibration (using monitoring loop). According to MIL-STD-461 you only have to calibrate 110 dBpT@1 kHz.
We want to do an other method of calibration and test:

- Translate the limit level magnetic field curve (dBpT) to a current curve (dBuA). Manual or Radimation could do this by adding a correction factor (183 dBpT = 15 amps).
- Do the magnetic field calibration (RS or CS?) on current.
- When the calibration is performed and finished, the calibration results can be stored to a .CAL file.
- To perform the real RS101 test, the earlier created calibration file (current) will be used to generate the requested magnetic field (Rs or CS?).
- Translate during test the current curve (dBuA) back to magnetic field curve (dBpT).

Is this possible and how to do this. We only use LF generator (Agilent 33220A) with oscilloscope (Tektronix TDS3054B) and current probe (Tektronix TCP202).
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joro
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Re: How can I perform magnetic field test for MIL-STD RS101

Post by joro »

Currently the calibration of the Magnetic Field is done using the measurement result of the magnetic field monitoring antenna. It is not possible to perform a magnetic field calibration based on the calculated current through the magnetic field generating loop antenna alone.

It is however possible to perform a Radiated Immunity Multiband Immunity test, where the current through the magnetic field generating loop antenna is regulated. To make this possible use the 'Magnetic Field closed loop method' testlevel in the multiband immunity test. That testlevel will adjust the generated power to the desired current, based on the known pT/A correction factor of the magnetic field generating loop antenna. In this setup it is needed to attach a 'Magnetic Flux Density' correction file as the second correction file in the device driver settings of the magnetic field generation loop antenna.
No calibration at all is needed to make this possible.
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joro
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Re: How can I perform magnetic field test for MIL-STD RS101

Post by joro »

We have created two different application notes that explain how the magnetic field tests can be performed in RadiMation.
It primarily contains the same information as shown, above but contains some more details and explanations regarding the equipment setup that has to be used.

The links are:
* Application Note 138: How to perform a magnetic field close proximity test
* Application Note 140: How to perform a closed loop magnetic field test
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