Just a dumb question, sorry if it is stupid.
From what I understood, you want to switch S1 and S2 for different measurements, without having to screw the cables on/off.
Wouldn't a cheap DiSEqC-switch as used for satellite TV reception do the job? The controller that implements the DiSEqC switching could be replaced by some simple logic (press button or whatever).
These switches are optimized for 950MHz-2150MHz, but will handle lower frequencies for sure. They come in all shapes and forms (2 in - 1 out up to 16 in - 1 out or even 16 in - 16 out).
https://en.wikipedia.org/wiki/DiSEqCAgain, sorry if this does not make sense, if so, please explain in a friendly way.
Regards,
Vitor