RF newbie here. Trying to learn about cables and losses and how they contribute to dynamic range.
I'm creating a shielding effectiveness system for enclosures with a 120dB dynamic range using signal generators, power amplifiers, transmitter and receiver antennas (such as 12" loop, biconical, dipole, log periodic and gain horn antenna for different frequency ranges) pre-amplifier and spectrum analyzer. The frequency range tested is 9kHz to 40GHz.
Thus, is it acceptable to use a long cable to increase loss in order to attain a dynamic range of 120dB, since the gain of the system is relatively higher? For example, the DANL of the spectrum analyzer is -130dB for 9kHz, hence by theoretical calculation and working backwards by taking into account gain of amplifier, antennas and pre amp, I am trying to figure out the cable length between each instrument in order meet the DR.
Also, would it make more sense to use different coax cables for different bands of frequency such as upto 18GHz, 26GHz and 40GHz when designing the system for each frequency band? Or would a 40GHz low loss coax cable meet the needs of the system all the way from 9kHz to 40GHz? However, the attenuation of the 40GHz cable at 9KHz is almost negligible which makes it hard to attain the desired dynamic range.
Any advice on cable lengths and losses would be appreciated as currently I'm working on determining the length of the cable from signal generator to amplifier, amplifier to tx antenna, rx antenna to pre amp and pre amp to spectrum analyzer in order to achieve a DR of 120dB for various frequencies between 9kHz to 40GHz.