"JN" wrote in message
...
I thought Richard's statement that modeling would tell you about how the
design might perform, was good advice. If you use EZNEC, I'd be willing
to help you if you dont already know how to use it to model your antenna.

Jerry KD6JDJ


Jerry, thanks for the offert.
I dont know how good these modelling programs are in this situation.
But if it is easy, so could somebody do the following:

Take 20m of wire, that is half of a dipole.
Put a 1/4 electric wavelength shorted stub for 10,1MHz so that the open
end is 7,25m from center and the shorted end pointing to the tip of
antenna. One side of stub is the 20m wire itself, like in the upper
picture. Ignore all velocity factors to make it sinple.
Now tell me what are the resonance frequencies of that kind of element and
if possible feed point impedande (80m and 30m)

I know I could do it myself but as you know learning to use a new program
reliably takes lot of time.

73 Jouko OH5RM

Hi Jouko

I suspect that you either understimate your ability to learn or you arent
aware of how EZNEC works. I submit to you that a modeling program is the
best method of establishing the antenna design you are describing. You can
probably learn everything you need to know about your antenna within a few
hours of thinking on your own. You dont need to attend a class room course
on use of the EZNEC program.
I considered computer modeling to be beyond my ability till Richard Clark
encouraged me to 'just try it'. I tried it, and I consider the program to
be the best tool a HAM could have for developing antennas. I am sure you
will figure out how to model your "trap" antenna and learn how well it will
work for you within a very short time. You even have access to some EZNEC
experts from this rraa group. Try it, you'll like it.

Jerry KD6JDJ