Recently when I said I was building one of these, some folks
wanted my evaluation of it when it was completed. I've
misplaced your emails (I hate when that happens!) so will
post it here and hope Kevin doesn't mind.
I built a "10 element" UHF version. One minor concern: I
couldn't change the SWR at all by moving the decoupling
sleeve up or down. However, it's OK since the SWR minimum
is exactly on my design frequency. Impressive.
I was actually shocked to find the SWR did not change
appreciably between top mounting, side mounting at 1/2 or
1/4 wavelength. I expected it to "complain" about the
nearby tower when side mounted. It doesn't even seem to
notice.
Unfortunately I don't have much to compare its performance
to. The previous antenna was a Cushcraft 4-pole dummy load
at the same height. The coaxial collinear provides MUCH
better coverage (no surprise there <BIG grin>). I have a
VHF repeater at the same site (1 dB less power into a 5 dB
gain commercial StationMaster). Over flat terrain VHF and
UHF coverage is very nearly identical. In rolling hills VHF
is generally better, as you might expect. In mountainous
terrain VHF sometimes has the edge, other spots the UHF
wins hands down. I wish I could offer more meaningful
comparisons. I'm quite happy with it and plan to build more
of them for other sites and applications.
Paul N1BUG
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