[TowerTalk] Two signals on the same frequency?

Jim Brown jim at audiosystemsgroup.com
Sun Aug 14 14:23:10 PDT 2011


On 8/14/2011 1:48 PM, Chet wrote:
> A hypothetical question:

Study the fundamentals of antennas, antenna arrays, and fields in the 
ARRL Handbook and ARRL Antenna Book. The short answer is that the 
signals from multiple antennas will ADD algebraically, taking their 
magnitude and phase into account. That is, in some directions they will 
be exactly in phase and will be stronger, in other directions they will 
be varying degrees of out of phase and either add less, or cancel each 
other. if they are equal in level and 180 out of phase, they will cancel 
perfectly.

EXACT:LY the same thing happens with reflected signals -- the vertical 
patterns of simple dipoles and vertical antennas are the result of 
reflections from the earth either adding or cancelling the direct 
signal.  Ditto for multi-path, and even for much of what we call 
selective fading.

73, Jim K9YC


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