Coaxial cable for radio astronomy from Norman Pomfret

Co-axial cable Impedance.  Matching impedance is not too critical when you are not transmitting POWER. where out of phase reflections can cause much higher voltages to be created often referred to as Meltdown especially where semiconductors are used. In days of old when Valves were the norm, Flashovers or ‘arcing’ (across air spaced capacitors) were common.  Especially when It was common to have a few hundred volts (or more) in the PA stage of a transmitter.  That takes me back to a time when I was a young trainee engineer, now a very long time ago.

If using various cables for a Receiver’s input, it is the integrity of the co-axial cables inner and outer and their isolation from Ground that matter.  as well being able to carry a radio signal at the frequency of interest.  Also the avoidance of interference or noise  ‘QRM’,   this latter term is from amateur radio and/or HM forces. 

Best wishes

Norman   M0SXF