How is a jig correction factor determined?

[solutionseeker]

If the jig is not "Configurable" there is a default correction factor of 9.5dB (theoretical value). How is it taken into account the presence of a correction factor? Its value is added or taken as is?

I explain with an example:
At 150kHz the real correction factor of my jig is 10dB, so it is written in the correction file. What is the behavior of RadiMation? Will it take 10dB as the total transfer correction?

[joro]

If a jig is not 'configurable' the correction factor depends on the brand and the type of the calibration Jig.

There are two categories of Injection devices:

• 50 Ohm. Like: Luthi CR 100 A, Tegam 95241, FCC BCICF
• 150 Ohm. Like: Luthi EM 101, MEB KAL-M2, MEB KAL-KEMZ, FCC F-203I-CF-23mm

Depending on the used injection device, a matching calibration jig is necessary to correctly calibrate the injection device. Based on the impedance of the injection device, the calibration jig should be corrected with a value.
In RadiMation we use the principle that we already programmed the correct correction value in the device driver of the calibration jig. This simplifies the implementation of our software, as you only have to select the correct device driver, and RadiMation automatically knows the correct correction value for the calibration jig.
So the device drivers for the calibration jigs for the 50 Ohm injection devices already have an internal correction factor of 0 dB. And the device drivers for the calbiration jigs for the 150 Ohm injection devices already have an internal correction factor of 9.5 dB (9.5424 dB to be more exact).

We are aware that it is not very clearly visible which correction factor is used inside a device driver of the calibration jig. That is why the newer device drivers, report the frequency range and the correction factor that is programmed inside the RadiMation device driver of a calibration jig. When you want to retrieve this information just press the 'Advanced' button on the device driver configuration window. See the following screenshot:

Advanced window of a calibration jig

calibrationjig.png (85.48 KiB) Viewed 12727 times

As can be seen, this EM101 calibration jig is using an internal correction factor of 9.5 dB (In reality it is 9.5424 dB, but it is only shown in a 1 digit precision).

If you want to use another correction factor for the calibration jig, it is possible to specify an additional 'transfer correction file', which specifies the additional correction on top of the already preprogrammed correction factor. So in your example, a 0.5 dB correction file should be attached to the calibration jig device driver. In that situation the total combined correction factor of 9.5 dB and 0.5 dB will result in the 10.0 dB correction factor, which will be used by RadiMation during the conducted immunity calibration.

I hope that this clarifies how the corrections for the calibration jigs are working and should be configured.

[labemcteseo]

Hi there!
I have a question about Configurable Calibration Jigs.

The window coming up with Advanced button shows the possibility of inserting the impedance of the jig: for example, a jig for CDN will have 100Ohm value.
Is it necessary to insert also the correction of 9.5dB in the field present in the driver window?

Thanks and regards!

Claudio Stazzone

[joro]

Hello Claudio,

for example, a jig for CDN will have 100Ohm value.

I assume that are using a jig for a CDN where the jig has 100 Ohm resistors in the connection. In this case you are using a 150 Ohm system (as the 100 Ohm resistors are in series with the coax which already has a 50 Ohm resistance).

The calibration jig value (as a factor or as a resistance) is only used for a conversion of the impedance of the CDN to the 50 Ohm typical impedance of the coax cables and powermeters.
In some RadiMation device drivers a resistance should be specified, and in other device drivers a calibration jig factor should be specified. If a resistance should be specified in a device driver, the calibration jig factor is calculated using the formula:

calibration jig factor = 20 * log10(<resistance [Ohm]> / 50)

For a 150 Ohm system the correct jig transfer factor is 9.5 dB. Depending on the selected calibration jig device driver a calibration jig factor of 9.5 dB should be selected:

Calibration jig factor of 9.5 dB for a 150 Ohm system

calibrationjigfactor.png (6.81 KiB) Viewed 10151 times

or a resistance of 150 Ohm should be specified for the 150 Ohm system:

Calibration jig resistance of 150 Ohm for a 150 Ohm system

calibrationjigresistance.png (8.35 KiB) Viewed 10151 times

For a 50 Ohm system, (where no 100 Ohm resistors are included in the calibration jig) the calibration jig factor should be 0 dB:

Calibration jig factor of 0 dB for a 50 Ohm system

calibrationjigfactor50.png (8.54 KiB) Viewed 10151 times

or a resistance of 50 Ohm should be specified:

Calibration jig resistance of 50 Ohm for a 50 Ohm system

calibrationjigresistance50.png (8.31 KiB) Viewed 10151 times