George Cutsogeorge writes:
>
>
> In using YT to try and determine the best separation for a pair
> of 40 meter beams and my terrain, the following happened: I
> started with a spacing of 100 feet and gradually raised the
> bottom antenna while observing the peak gain. To my amazement,
> it kept increasing with each increment. Surely it would decrease
> at some point as the spacing got smaller and smaller. Well, it
> kept on increasing all the way to zero spacing and that's where I
> quit.
>
> It does the same for flat ground or my terrain. What's going on
> here?
Maybe this:
(from the YT manual)
The internal Yagi model in YT is simple and does not compute
interactions between individual Yagis in a stack -- YT assumes
that each antenna is a point source. For antennas stacked less
than about a half wavelength apart this is not a problem.
For example, you should be cautious specifying spacings less than
about 20 feet on 20 meters (and proportionately scaled on other
bands) because of mutual-coupling effects between real antennas.
--
George Fremin III You know you've achieved perfection
Johnson City, Texas in design, not when you have nothing
K5TR (ex.WB5VZL) more to add, but when you have nothing
geoiii@kkn.net more to take away.
512-416-7010 -- Antoine de Saint-Exupery
http://www.kkn.net/~k5tr
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