Wednesday 8 February 2017

Network Analyzer HP 8752A Calibration


How can I do a two-port response calibration to measure S-parameters (Reflection and Transmission) for an HP 8752A Network Analyzer?



The DUT (two coils, one in air and one in salt-water) is connected to the analyzer with two cables (one cable is connected to Reflection port and the other one to Transmission port.)


The manual is not helpful at all, VERY confusing. When doing calibration, should I connect the two cables together, then one head to one of the ports, the other head to the calibration part?


In response to answers:


Yes, I do have a cal kit.


The problem is that I need to calculate Max Available Gain and for that I need to find the S-params.


My experiment is with two small coils, both in air, one is constant and the other with change distance. One coil (coilA) connected to Refl port of NWA (using a cable) and coilB to Transmission port (using another cable). Each time I change distance one cm, I run a Matlab simulation to get the graphs (mag and phase.) Then I have to switch coils (coilA to Trans port and coilB to Refl port.) Same dist. Run Matlab again.


Then I change the distance one cm, run matlab, switch coils, run matlab again. Of course saving the data.


So basically it is measuring reflection response and then transmission response at each port for each coil.


Now, My question is about how to calibrate for this specific type of measurement? I heard that I should connect the two cables together, then one head to the NWA's port (say Reflection, if I'm doing Reflection response measurements.) and the other head to the calibration part (say open or short). Then, on the NWA press the Measurement button and select the type of measurement I want, say Response. Also, I should set the Number of Points, Start freq, and End freq. Then press the CAL, CAL Menu, Response, then Open (F)/Short (F)/Through, Done Response, (Re)Save to register.


I performed one calibration for Reflection response, save it in register 1, then calibrate for Transmission response and save it in register 2. This is because when I'm running the Matlab simulation and then need to switch coils, I can do that without having to calibrate again. I can just recall the calibration using Recall button.



I have to add that I have already read HP 8752A NWA manual, from beginning to end, not much helpful.


I think there were mistakes there: So I was told many times from different people that when I want to do Transmission (or Reflection) calibration, as a part of the calibration step I have to press the Measurement button(key), then select Transmission (or Reflection.) Then continue with performing the calibration. However, in the manual it is not said so which seems odd!


Anyway, I hope all these information make sense and is not overwhelming or confusing. Also, hope to hear some feedbacks and ideas. I'd greatly appreciate.




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