In a message dated 2/24/2007 4:25:59 A.M. Greenwich Standard Time,
jimlux@earthlink.net writes:
The best way to answer these questions is to get a copy of HFTA,
which comes with the ARRL Antenna book. It lets you model the pattern
of stacked antennas, varying spacing, etc., and factoring in your
terrain, as well. You just select the kind of antenna (e.g. 5
element beam),
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
But there is a rub to doing that, isn't there? I think the program assumes
a standard length boom for 3 el and a standard length for a 4 el and so on.
If one uses the 4 element STeppIR for 10 will it not behave more like a 6
element in a stack since it has a boom which is what a usual 6 element has? I
believe the boom on the SteppIr is around 32 feet and the usual 6 el 10 meter
is around 27.
What this means to me is the antenna will "behave" more like a 6 el in
stacking since the boom length is a primary consideration in stacking
distance.
The same concept is true for 15 for the SteppIR, with the boom somewhere
between what a 5 or a 6 element standard Yagi would have ...32 ft.
Because of the above reasoning, I have input the 4 element on 20, a 5 el on
15 and a 6 el on 10 on the HFTA program in computing stacking distances...not
the standard 4 element for all bands.
I'd like to hear from others on this idea, since I am in the middle of
modeling the three high stack of SteppIRs on that HFTA program. I have a wide
range of available heights and want to do it right the first time.
Bill K4XS/KH7XS
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