[TowerTalk] Two signals on the same frequency?

[K1TTT]

Separate amplifiers could also be problematic unless very carefully designed
and tuned to keep the phase delays the same when changing frequency across a
band.


David Robbins K1TTT
e-mail: mailto:k1ttt at arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://k1ttt.net
 

> -----Original Message-----
> From: Jim Brown [mailto:jim at audiosystemsgroup.com] 
> Sent: Sunday, August 14, 2011 21:48
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] Two signals on the same frequency?
> 
> 
> On 8/14/2011 2:23 PM, Jim Brown wrote:
> > The short answer is that the
> > signals from multiple antennas will ADD algebraically,
> 
> One VERY important point is that for the signals to ADD, they must be 
> SYCHRONOUS -- that is, on precisely the same frequency, 
> coming from the 
> same oscillator.  In practical terms, this means a signal 
> generated by a 
> single transmitter, then fed to two power amps that feed different 
> antennas. Or a single transmitter (with or without a single 
> power amp), 
> split between multiple antennas.
> 
> If the two signals were not synchronous (that is, from two 
> independent 
> transmitters) their phase relationships will be random, and 
> addition and 
> subtraction will be quite unstable and unpredictable.
> 
> 73, Jim K9YC
> _______________________________________________
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> 
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