Hi researchers,
I need to measure some coax cable that I use to feed my antenna. How can I make sure that those cables works fine , and how to do it with Vector Network Analyzer ? Should I look S11,S21 , if yes what should I expect from those parameters ?
Thanks in advance...
Yasin Hoşgör your starting point should be the coax cable specifications, as specified by the manufacturer. It will tell you what are the specified characteristics for the cable. Only reputed manufacturers provide such data sheets; clones may not do so.
Yes they way to go is a proper reflections and transmission measurements with a good VNA; sometimes the "other "end is not accessible then one can do it only from one side.We have a great experience here with this kind if problem ; dont hesitate to send me an e-mail:[email protected]
It is good practice to look at both S11 and S21 responses.
S21 (frequency vs gain) tells you the cable loss. Note you have to calibrate the VNA before you measure the cable so that the VNA corrects other losses associated with equipment including its cable. The loss of the coax depends on its length, frequency, and the material it is made of but it should have a lower loss in the frequency range that you intended to use the antenna.
S11(frequency vs reflection) tells how much of the power makes it through the other end of the cable and how much of it is reflected. A rule of thumb is S11 < -10 dB in the frequency range of your antenna. S11 of -10 dB means 99% of the source power can be delivered to the antenna.
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