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Old November 21st 03, 06:17 PM
John Doty
 
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In article , "w4jle" W4JLE(remove this
to wrote:

Believe what you will, the law of reciprocity will ignore your beliefs
and continue to function.


1. It's only a "law" for scalar radiation (like sound), not vector
radiation (radio). To be sure, it's a fine approximation for most HF
antenna systems, but watch out a microwave frequencies, especially if your
antenna system contains a "circulator".

2. In the cases where reciprocity applies you would be correct to say that
it requires that the antenna directivity and efficiency are the same for
transmitting and receiving. It does not follow, however, that a poor
transmitting antenna is necessarily a poor receiving antenna. Efficiency
matters much more when transmitting than it does when receiving.

Franks's observations are correct, and can be verified if you do a
detailed signal to noise calculation. You could also try the experiment
yourself.


"Frank" wrote in message
news:01c3b0a2$989de120$0125250a@cqvdqntcxxawvjpo.. .
Wes Stewart ...

^ Antennas are reciprocal, if they wouldn't work well for
^ transmitting, they will work equally poorly for receiving.

I don't believe that. It's been my experience that an antenna used for
receiving will function satisfactorily over a much broader range of
conditions (environment, antenna length, etc.) than it will if used for
transmitting under those same conditions.

Frank




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