Guy Olinger, K2AV wrote:
>
>Structural return loss is what comes back due to any imperfections in the
>cable itself, even if properly terminated at the other end
Thank you - I just learned something.
>
>Hmmm, 30db RL = 1.001:1 SWR? Talk about indiscernible needle movement...
>
If you're using a return loss bridge (three resistors and a diode,
details in QST etc) you see a very sharp, deep null in the reflected
signal. The better the match, the deeper the null. That's one of the
things that makes RL a useful alternative to VSWR.
Another area where it's useful is where you're asking how much the cable
loss "improves" the apparent match at the TX end.
How much does a 3dB cable loss improve the VSWR? You need a calculator.
How much does a 3dB cable loss improve the RL? Exactly 6dB (3dB each
way).
73 from Ian G3SEK Editor, 'The VHF/UHF DX Book'
'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.demon.co.uk/g3sek
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