Guys,
I'm interested in "stacking" a Cushcraft rotatable dipole (half their
40cd2) with my 4 element GEM 10-15-20 meter quad. Stacking isn't quite
correct. I plan to mount it parallel to the boom and 1 foot above it.
The GEM quad boom is only 16' in length.
I did some calculations with K6STI's AO program to assess the
interaction. There was absolutely no impact on the quad with the
shortened dipole modeled as a solid 1" full length dipole. (Didn't know
how to model the lumped constants and capacity hat of the real antenna)
This was not entirely unexpected. Metal booms don't impact the quad's
performance either.
Now for the key question. Does the boom (and tower) impact the rotary
dipole. Again I modeled the dipole, first in free space. Then I
modeled it with the 16' boom and 75' tower (20" diameter). There was
absolutely no impact again.
Now for what Cushcraft says. I sent a note about possible interaction
to Cushcraft. They say the presence of the boom will seriously detune
the rotary dipole and mount it at right angles to the boom. This
arrangement , when modeled, is detrimental to the quad.
So I have contradictory information. The antenna modeling program
contradicts Cushcraft's statement.
Any thoughts on who is right-- or do I flip a coin and actually try it
with both orientations and find out both are wrong?
73 de Brian/K3KO
Vance Net Inc
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