If say I wish to measure a radar's 2 port characteristics (it sends to itself via a distance D air link)

Can I make an experiment that I use Network Analyzer to measure it transmitting signal to another antenna B spacing distance D LOS, then cascade the resulted s2p file in the configuration such that

[port 1, port 2] --- [port 2 , port 1] , and divided the dB(s21) and dB(s12) by two respectively and subtract by 3 dB to get the 2 port metrics?

I am not quite familiar with the operations/tricks on scattering parameters, could anyone recommend resources that I can refer to?

Thank you very much!

  • \$\begingroup\$ I cannot understand where your reference planes are. Please elaborate on your proposed measurement setup. What piece of the radar do you wish to measure? its mismatch, the swr between the radar and the antenna ? or the radars maximum range ? \$\endgroup\$
    – user55924
    Sep 19 '17 at 15:14
  • \$\begingroup\$ @user55924 Yeah I shouldn't say radar.I wish to establish a link model between a receiver and a transmitter, to verify my link budget. So I was thinking to use NA to measure 2 port s parameter, then put into my circuit simulator to simulate. However, one of the two antennas I made for this experiment has terrible match at desired frequency. I don't bother making another good one. So I was thinking to use the bad antenna to conduct the experiment anyway, then cascading two s2p module back to back, reference to same ground, to get a quick and dirty verification. don't know how wrong it can be. \$\endgroup\$
    – Eagle Shou
    Sep 20 '17 at 5:29
  • \$\begingroup\$ @user55924 For explanation of radar, I can't afford doing the complete measurement in specialized lab. I only can use a network analyzer in school nearby. My experiment needs to be set up such that those bouncing back from scattering/reflection is very small comparing to my direct signal tranceiving link. Ultimately, I want to use a circulator to reduce the need for two antenna into one. So indeed the transmit-receive s-parameter model for one antenna is desired, if that is theoretical sounding, I prefer to use a measurement model in circuit simulation. \$\endgroup\$
    – Eagle Shou
    Sep 20 '17 at 6:19
  • \$\begingroup\$ I would not do that. In my eyes, the measurement would be too inaccurate. I would measure each 2-port system component individually, then figure out the reflection coefficient and gain of your antenna in the relevant direction. Then combine all the 2-ports on each side of the tx-link, and use the friis transmission equation with the antenna gain and reflection(loss) to get your base specs of how the antenna impacts the system. Then use equations to figure out estimates on fading and such. \$\endgroup\$
    – user55924
    Sep 21 '17 at 10:58

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