[TowerTalk] K6STI Receiving loop question

[Pete Smith]

OK -- well, the program says that at the RX end this particular length of 
cable and other conditions presents a 23+smallj mismatch to a presumably 
50-ohm receiver.

The point I was trying to make is that this magnitude of additional loss is 
of little consequence in a simple low-band receiving antenna.  Is that wrong?

73, Pete N4ZR

At 06:40 PM 11/18/2004, Tom Rauch wrote:

> >Well, as a 'frinstance, if he's using RG-6 75-ohm cable,
>say 100 feet
> >long, and the antenna is presenting 240 ohms to the cable,
>on 1.8 MHz the
> >additional loss in the cable due to the mismatch is about
>.4 dB out of a
> >total of .8db, according to TLW.
>
>
>The source never sets feedline SWR. The SWR on the line in
>receiving is set by the receiver, not the transmitter. The
>receiving feedline loss is calculated using receiver input
>impedance. The antenna mismatch only adds mismatch loss at
>the source (the antenna).
>
>Lossy systems are often not bilateral. Take for example an
>antenna tuner. When it has loss, the impedance
>transformation is not the same in both directions.
>
>If I have a 35 ohm load I can match it to a 50 ohm
>transmitter by adding a series 15 ohm resistor. The load,
>looking back at the transmitter port, sees 65 ohms when a 50
>ohm receiver is attached. Woops!
>
>73 Tom
>
>
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