[TowerTalk] TowerTalk Digest, Vol 125, Issue 64

[Jim Brown]

On 6/1/2013 9:34 AM, GEO Badger wrote:
> Alas, that is not true. Gain is reciprocal on antennas.
> http://www.ece.rutgers.edu/~orfanidi/ewa/

Yes, BUT -- on the HF bands, what usually matters on RX is DIRECTIVITY, 
not gain.  That's because what we hear is limited by noise picked up on 
the antenna, not circuit noise in the RX itself. Also, antenna 
directivity is three dimensional -- their vertical and horizontal 
patterns can be quite complex, and most practical antennas are polarized 
-- that is, they transmit and receive more energy horizontally or 
vertically polarized.  Those properties are also reciprocal, and they 
can either enhance receiving or make things worse, depending on the 
directions from which signals and noise are arriving, and their 
polarizations.

73, Jim K9YC