----- Original Message -----
From: "Dick Green WC1M" <wc1m@msn.com>
> Hi. I'm trying to use EZNEC 4.0 to determine whether there would be any
> interaction between a 2-el 40m beam at the top of a tower and various
> beams
> placed lower on the tower. For example, I've tried putting a 40-2CD at
> 105'
> over a 3-stack of 4-el 15m monobanders at 90'/60'/30'. The model showed no
> significant difference in the 15m pattern with or without the 40m beam,
> and
> no significant difference in the 40m pattern with or without the stack.
> Same
> story for 3-stacks on 20m and 10m at the same heights. I even tried
> putting
> a 5-el 15m beam at 100', only 5 feet from the 40m beam, and got no changes
> in pattern for either antenna. Seems to me that there would be some
> interaction between 40m and 15m antennas spaced that close. Is that
> incorrect, or is there a problem with my model?
>
Dick,
If I am not mistaken, the lumped loading on the 402-CD
causes the 3rd harmonic resonance to fall in the 17 meter
band instead of the 15 meter band as you would get with
a full size element. If you modeled the 402CD correctly,
this might explain why the interactions on 15 are smaller
than expected.
73 de Mike, W4EF..................
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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