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Design >> RF Design >> Testing matching circuit on VNA
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Message started by smwk on Jan 27^th, 2014, 10:02am

Title: Testing matching circuit on VNA
Post by smwk on Jan 27^th, 2014, 10:02am

I have made a matching circuit by matching (50) ohm to (0.89-j*2.3). Now I want to test the matching circuit fabricated on microstripline on VNA. The problem for me is how to give a load (0.89-j*2.3) on the VNA port to test the circuit and verify the practical results.

Title: Re: Testing matching circuit on VNA
Post by RFICDUDE on Jan 27^th, 2014, 5:14pm

It is not common to attempt to program the VNA to imitate a specific load impedance.

The VNA is typically used to measure the s-parameter response of a component. The s-parameters are generic in that they can be used in simulations where the port impedance is not the same as the VNA used during the s-parameter measurement. Therefore in the simulator you can use the measured s-parameters and put your 0.89-j*2.3 ohm load on one end and measure the impedance at the other end to verify the match is correct.

I hope that this is helpful to you.

Title: Re: Testing matching circuit on VNA
Post by smwk on Jan 27^th, 2014, 10:50pm

Thanx RFICDUDE ...
My concern is testing on VNA
I have already simulated the circuit in ADS where i m getting good match i.e. getting S11 equal to -28 dB. But after making the matching circuit practically I want to test it on VNA inorder to see the difference between the simulated result and practical result. On VNA i can give 50 ohm on one port but cant give (0.89-j*2.3) on second port . So how to measure the practical result?
hope u got my point...

Title: Re: Testing matching circuit on VNA
Post by aaron_do on Jan 28^th, 2014, 4:49pm

Hi smwk,

he got your point. What he said was:

Just measure your matching network with a 50-ohm load. You will get a set of two-port s-parameters. You can then use those s-parameters that you measured in a simulation with whatever load you want.

regards,
Aaron

Title: Re: Testing matching circuit on VNA
Post by smwk on Jan 28^th, 2014, 11:57pm

Thanx aaron..and RFICDUDE as well.
Now I got your point. Actually you explained it in simple words. Thanx