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S11 reads -7dB before calibration, correct?

Question asked by meta5718 on Oct 30, 2013
Latest reply on Oct 30, 2013 by meta5718
I am new to VNA and I have a quick question.

It is a 8720D VNA, each test port has an adapter from 3.5mm to N-type (female). The machine was calibrated by a vendor within a year; not sure what was calibrated exactly (to the 3.5mm test port only, I assume).
After turning on the machine, without any SOLT calibration, the S11 and S22 reads -6 to -7 dB. The two 3.5mm to N adapters are always on. I have a N-type short. And with the short on, the S11 and S22 are about the same as open, -6 or 7 dB. Frequency was 2 - 10 GHz.

My question is whether this is normal or not? I thought with open (NOT open calibration kit though) or short, the S11 should be close to 0 dB. Although it may not be exact and that is why SOLT calibration is needed, is it expected to see such a big "loss"?

Thanks for your help!  

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