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Mixed 75Ohm / 50Ohm measurement on ENA E5071C

Question asked by hhaisch on Jul 24, 2008
I have a DUT with 75Ohm input and 50Ohm output.
I would like to to measure the S-Parameters of this device, especially the S11 of the 75Ohm input, S22 of the 50Ohm output and the S21.
I do a 50Ohm ECAL then I use the Minimum Loss pad, to get from the 50Ohm system to the 75Ohm interface.
When using the MLP's s2p file (which was generated using the adaptercharacterization macro) the best S11 I can get is about 14dB (e.g. when using the 50Ohm load of the 85036B calkit).
S21 seems o.k.

How can I improve the S11 measurement of the 75Ohm DUT interface?

I could do a 50Ohm ECAL, use the MLP deembedding for the S21 / S22 measurement and a seperate 75Ohm 1-port cal across the MLP for the S11 DUT measurement . However this procedure is some what impractical since it requires 2 seperate calibrations and loading 2 states.

Is there a more practical way on the ENA?

Thanks
Hansjoerg  

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