[TowerTalk] Why does KT34XA/KT36XA stink on 15 ?

[Jim Brown]

On 6/2/2022 1:14 PM, Steve London wrote:
> There is a 40 meter beam about 30
> feet above it, but the 15 meter SWR does not change when either the XA or
> 40 is rotated, so I don't think there is significant interaction.

Hi Steve,

I've used NEC to study the possibilities of interactions like this on 
other bands. The method is pretty simple. Build a model of a simpler 
antenna like a 2-3 element 15M Yagi, and add a 40M dipole spaced like 
your antenna is. Build that dipole with a load at the center that you 
can set to either a short or an open. Driving the Yagi, set the visual 
display of the model to display currents, and look for current in the 
dipole. Do this for various positions of the dipole with respect to the 
forward direction of the Yagi.

If you find current, I'll try to figure out what you might be able to do 
in the 40M feedline to kill it.

73, Jim K9YC