[TowerTalk] Antenna Interaction

[Jim Brown]

On Sat, 16 Jun 2007 22:50:05 -0700, Dave Hachadorian wrote:

>If f/b is degraded, try lengthening or shortening the dipole's
>feedline to detune it

A much better way is to add one or two good common mode chokes (some 
turns around some ferrite cores) to the feedline. See the tutorial on my 
website.

http://audiosystemsgroup.com/RFI-Ham.pdf

Study the section in the tutorial first about baluns and chokes, then see 
the section on using chokes as "egg insulators" in the feedline to 
prevent them from interacting with other antennas. 

For details of how to wind the chokes, see the following internal 
communications I shared with other guys who were doing their own choke 
research. I haven't had time to finish the measurements (I've been on the 
road a lot) and revise the tutorial to reflect the new data. 

http://audiosystemsgroup.com/ChokeMeasurementsK9YC-K6TD042207.pdf

http://audiosystemsgroup.com/ScalarChokeMeasurements1.pdf

73,

Jim Brown K9YC