If you MUST use coax then prefer 75 ohms. Go for the greatest overall
75-ohm coaxial diameters. The greater the overall diameter the smaller
the attenuation in terms of dB per 100 feet.

There's no need to impedance match a 75ohm line to a 50-ohm receiver
for receiving purposes. The mismatch loss is quite small.

What matters is a severe mismatch between the antenna impedance and
the line impedance which will occur on some of the higher frequency
bands.
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Reg.