Topband: Polarity and Phase

[Jim Brown]

On Wed, 14 Apr 2004 14:55:30 -0400, Tom Rauch wrote:

>If I take two omni-directional antennas and run them into locked receivers,
>I can create any pattern I like with phase shift in the receivers. If I
>unlock the receivers (just a few Hz or less off), the effect is the same as
>having constantly varying phase in the antennas. At any instant of time the
>signals might be in phase, in quadrature, or out-of-phase.

If the receivers are tuned to different frequencies, the resulting
audio signals are of different frequencies, and phase has no meaning! 
Phase is only defined for sine waves of the same frequency!  

>If flipping phase on the audio output is not the same as flipping phase on
>the RF input, why does the system behave this way?

You are not "flipping phase," you are reversing polarity. And I agree
that reversing polarity of one source in the RF chain CAN be equivalent
to reversing polarity of that source in the audio chain, PROVIDED THAT
the receivers are locked so that the signal chain is coherent (that is,
phase has meaning), as you have described. 

BTW, while I have not had the luxury of diversity reception, but I
strongly agree with your outline of how it ought to be done. 

73,

Jim