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Hi Oristo
My comment regarding about "waste of time" regarding S21 measurements was solely based on how to save a S21 sweep and convert it from transmission to reflection.
There are other option which I have tested to night where an ordinary SOL calibration is done ether in shunt mode or Serial mode.
The shunt mode where a T-Adaptor is inserted between the two SMA male male test cables and a SOL calibration done at the third leg of the T-Adaptor. If the T-Adaptor is FFF then use the male calibration kit and in the NanoVNA-Saver you may use either ideal or the settings I published for male kit. If you use a FMF T-adaptor allowing a female bulkhead/PCB edge adapto to be fitted where the DUT is soldered between center pin and ground, then calibrate with the female calibration kit setting in the NanoVNA-saver. I have attached screen copies of the shunt method testing a 10K resistor and it works actually when seeing the parallel R and X values in the data fields for the three marker. The reading a fluctuation due to noise but by continuous sweeping and using the NanoVNA-saver averaging function it is actually not that bad. However the Shunt method are only optimum for impedances from 0 ohm and up to some 1K ohm
For the S21 series SOL calibration I used the three pin pin adaptor seen on the picture constituting Short Open and Load (two 100 ohm 1% SMD resistor soldered to the pins) and the screen copies demonstrates clearly that measuring 10Kohm is piece of cake when studying the marker data as parallel R and X. The window for R+jX is on the other hand "terrible" only because the R+JX read out and due to the 110fF measured as the capacitance of the two pins to which the 10K resistor is soldered. Ig I had used an open standard like the adaptor with 10kOhm fitted the this shunt c would have been smaller and been the shunt C of the SMD resistor and the added fringe C due to the solder added to the end of the SMD resistors. As you see when you have control of you test setup like I have demonstrated. The it is possible up to at least 100MHz to reach accurate measurement. The traces in the Smith chart shows also for the shunt method the added delay due to the Bulkhead adaptor (as the calibration is at the SMA male reference plane). It can be tempting to use the Electrical Delay in the NanoVNA menu but due to the lag of error correction in the NanoVNA it does not work satisfactory.
Final remark:
Prior to do these two new calibration methods for the NanoVNA in conjunction with the NAnoVNA-Saver do a full SOLT calibration with the two male male test cables fitted from the NaNoVNA menu and save to C0. It is always a good idea to have these two test cables fitted. This calibration is essential for the NanoVNA-saver to build upon despite it does account for the delay of the female female adaptor both for S11 and S21 calibration but no to do anything about and that is why the Electrical delay does not work properly.
Have fun
Kind regards
Kurt



-----Oprindelig meddelelse-----
Fra: [email protected] <[email protected]> P? vegne af Oristo
Sendt: 17. november 2019 21:52
Til: [email protected]
Emne: Re: [nanovna-users] Increasing measurement range (ohms) ?

Hi Kurt -

Thanks as always for your expertise and patience for explaining VNA best practices!
This second paper motivates mastering T adapter techniques, particularly for low impedances.

Thinking of finding a way to measure in S21 mode with the NanoVNA is "waste of time"
as it requires that both the Ch0 and Ch1 output/input impedance is pure 50 ohm.
In the appendix2 of one of the report S21 measurement documented.