calibration of VNA with 180 hybrid

[Jone]

+calibration kit +vna

I'm measuring S11 for my chip (differential topology) which required to use a hybrid 180 degree. How to calibrate the differential output? That is, how should I calibrate the VNA when the hybrid is connected?

Since I have just one SMA calibration kit, I used both of the male and female to calibrate. Match and Open are Ok, but Short gives some complains.

 

[Azulykit]

back to back calibration vna

Several comments

I have contemplated the difference between a balun and a 180 degree hybrid for a while and have come to the conclusion that while both have outputs that are 180 degrees apart there is another distinction. The balun is intended to convert from a single-ended to differential (or balanced) transmission line as well. The two devices are not completely interchangeable. You may be better served with baluns.

You may consider building a two part test fixture for your part that has a test coupon that mirrors the part test footprint but is connected back to back. You can then test the part and extrapolate the performance of the test part by de-embedding the measurement using the coupon measurement. Essentially you are looking at the difference between the two measurements with the VNA calibrated to the coax.

Buy a second calibration kit so you don't run short of standards.

VNA's exist with four ports and can make differential measurements directly.

 

[Kenent]

Is it not better to calibrate only one leg and keep the other leg match to 50 ohms? I am not very familiar with VNA myself.