[TowerTalk] return loss

[Guy Olinger, K2AV]

>Same difference. Return loss is the amount, in dB, that the
>reflected signal (power) is down from the forward or incident wave.
>The ARRL Handbook has a converstion nomograph. However,
>it is obvious that a 1:1 VSWR would be a very high value of
>return loss (>40 or 50 dB), and a short or very high
>SWR would yield a RL close to 0dB.
>
>I'm surprised that AEA is using RL as that is usually used in the 75 Ohm
world
>of cable television, whilst SWR is the 50 Ohm world of RF communications.
>Maybe I should introduce Towertalkians to SRL (structural return loss),
which
>is used to qualify hardline coaxial cables?

Return Loss... Brings back memories of my time working Network TV for AT&T.

A good thing that we don't have to worry about broadband ham signals
requiring 30 db of return loss or better on the transmission system to
prevent signal degradation. What we consider a "good" SWR bandwidth on an HF
beam would fuzz up a TV signal with all kinds of color smearing, etc.

Structural return loss is what comes back due to any imperfections in the
cable itself, even if properly terminated at the other end? Who sells the
really good network grade stuff these days?

Hmmm,  30db RL = 1.001:1 SWR?  Talk about indiscernible needle movement...

>
>73,
>Bob AA0CY
>20 years in the technical side of cable television
>


73, y'all

Guy
----------

Guy L. Olinger
k2av@qsl.net
Apex, NC, USA



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