[TowerTalk] Interaction between antennas

[David Hachadorian]

----- Original Message ----- 
From: "va3pl @ cuic.ca" <va3pl at cuic.ca>
To: <towertalk at contesting.com>
Sent: Wednesday, October 05, 2005 2:45 PM
Subject: [TowerTalk] Interaction between antennas


>I am installing my WARC Cushcraft A3WS + 30M kit 8 feet above my 
>Mosley
> CL36.
> Should I turn it 90 deg in relation to Mosley or the seperation of 8 
> feet is
> sufficient to heve both booms parallel which is prefered by me.
> Andy - VA3PL

It's almost impossible to predict such interactions. The most 
sensitive indicator that interaction is occurring is degradation of 
the f/b ratio on one or more bands. Measure the f/b of the CL36 before 
you put up the a3. Then put the a3 up, booms aligned. Remeasure the 
CL36 and measure the a3 vs. its specification. If f/b is degraded, try 
rotating the boom 90 degrees. If f/b is still degraded, you will need 
some different antennas.

It's easy to measure f/b:
1. Have a local ham friend 500 meters or more away transmit a carrier.
2. Turn the back of the beam toward your friend.
3. Note the s-meter reading.
4. Turn the beam toward your friend.
5. Crank in attenuators until the s-meter returns to the original 
reading.
6. Reads the f/b ratio from the attenuator setting.

Dave Hachadorian, K6LL
Yuma, AZ











































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