[TowerTalk] HFTA and diferent bands antennas

[Jim Brown]

On Sat, 24 Apr 2010 17:52:53 -0700, jimlux wrote:

>I don't know about that... That would imply a violation of reciprocity, 
>wouldn't it?

Not necessarily. See below.

>I would believe non-symmetric propagation via skywave, but not that the 
>"effective antenna pattern" is different for transmit/receive.

The word "effective" is an important qualifier here. What HFTA does is 
attempt to model interaction of the wavefront with terrain. So it isn't 
the antenna pattern that's changing, it's the interaction with terrain. 
Intuitively it seems possible that wavefronts traveling in different 
directions might interact differently.  Or maybe not. :) I slept through 
that part of physics. 

73,

Jim K9YC