Be careful when modeling antennas with offset feed. It's very difficult
to prevent common mode current flow on the feedline of offset feed
antennas. You might be able to keep the common mode current down to a
reasonable level with a couple of good current baluns spaced about a
quarter wavelength apart, but otherwise the feedline will be an
important part of the antenna and needs to be included in the model.
You'll have to include the whole conductive path to the Earth in order
to get good accuracy, and this path might not be easy or possible to
determine.

Roy Lewallen, W7EL

jimg wrote:
Hi. I'm looking for more creative ideas. I live in a typical suburban
setting. I have a 100' oak tree out back with a clear base of 65' on
to one side; 75' to the other. I've EZNEC'd a variety of antennas from
center fed (ladder line) inverted vee resonant at about 2.4MHz. Moved
to offset fed versions which works over more bands but still not quite
a low enough swr to load with a palstar balanced tuner on 160. Moved
on to a 'triangle' antenna made by adding a wire base to the inverted
vee about 2-' off the ground. Now I've got enough length, but the swr
is squirrely on all abnds because of the interaction of the short legs
(I guess it's a short delta with only the driven element.). So, it
appears I'll have to wait until the kids graduate and a move to the
countryside is in order.
I know it won't work as well as a wavelength loop with a huge mesh
metal fence counterpoise, but it would be nice to try and ragchew on
160m while the sunspot cycle is zilch. Any weird topologies come to
mind? And still let me load up 80/40m?
jimg
Oregon
USA