Hi Christian,
Thanks very much for your explanations.
I'm trying to understand your graph and how you are calculating the error in dB. So I thought I'd try this simple example:
Let's say I have a Load standard whose actual resistance is 53.265 ohms (i.e. Gamma is 0.0316 and Return Loss of 30 dB) and I calibrate my VNA with this standard as its 50 ohm load.
After cal, I measure S11 of this same load. Its Gamma is now 0 (instead of 0.0316) and the corresponding return loss is in the noise of the instrument.
The error in S11 (i.e. Gamma) could be plotted on your graph at the point where DUT Reflection = -30 dB and Load Reflection (Actual) = -30 dB.
But what would be the value of this point? I get a Gamma error of 100% (i.e. 100*(0-0.0316)/0.0316). How are you calculating the dB error of the S11 magnitude?
I'm sure I must be missing something straightforward (maybe it's too early in the morning!)
Again, thanks.
- Jeff, k6jca
