I've been working on a Shielding Effectiveness system of 120dB according to IEEE299-2006 standards. The frequency range covered is 9kHz to 40GHz.
I've designed it using an analog signal generator, power amplifier, antennas (varying antennas for varying frequencies), pre amplifier and spectrum analyzer. I would like to know how to choose a cable for the system. I figured RG213 would be a good choice, however if it necessary to use it through out the system all the way from signal generator to spectrum analyzer.
Any ideas or suggestions would be good. In fact, guiding the way on how to select an appropriate cable that would meet the aim of 120dB for the frequency range of 9kHz to 40GHz would be much appreciated.
Best Answer
RG213 is a badly shielded low cost cable for a few hundred MHz at most.
For your application you'll need 086 size rigid coax, just over 1 mm thick. Rigid or semi-rigid coax has a solid braid, so up to 100 dB screening. (but probably not at 9 kHz). At 40 GHz you'll need very thin coax, which is unfortunately very lossy.
Brace yourself for the price of 40 GHz connectors, hundreds of dollars each. You can't use N-type above 10 GHz or so.
You might consider separating your whole system into different frequency bands. The antennas and amplifiers will already be quite band-specific. Then you could use 141 or 250 size rigid coax for the lower frequencies.