[TowerTalk] 15 meter beam on 40 meter tower ?

[Jim Brown]

On 9/1/2022 11:09 AM, Kim Elmore wrote:
> I have a KLM KT-34A about 8 ft from and perpendicular to 40CD2. They each appear unaffected by the other, at least as far as VSWR values go.

I wouldn't expect to see interaction from the elements if they were 
perpendicular, but MAYBE from the boom.

An easy way to check for interaction between antennas is to model the 
victim as a dipole with the addition of the potentially interfering 
antenna as a dipole at the planned spacing, and look for current induced 
in the potentially interfering antenna when the victim antenna is driven 
at its operating frequency. If there is significant current, I'd start 
looking at it's vertical pattern, also varying the lengths of the 
interfering antenna to simulate the effect of reflector and directors of 
the interfering Yagi.

If interference disturbs the vertical pattern enough to matter, you can 
play with spacing until the effect is minimal.

73, Jim K9YC