At 06:57 PM 3/19/97 -0800, Brian K6STI wrote:
(quoting me)
>>If you want to really be surprised, compare 2-high dipoles with 2-high
>>yagis at the same heights. We really do spend a lot of effort for a few
>>db. For example, stacked dipoles at 97 and 69 feet show a gain of 10.3 dBi
>>on 20 meters; the gain of a stack of TH-7s is no more than 15 dBi.
>How did you obtain the values of L and C for the Hy-Gain traps in your
>model? I don't believe even Roger Cox knows them.
>
>
>Brian Beezley, K6STI
>k6sti@n2.net
Hi Brian -- You're right. The model I used is an idealized
TH-7 with no traps and cylindrical elements. That's why I said "no more
than" 15 dBi. I suspect there's something else going on in trapped
antennas (other than losses through trap heating) that costs forward gain.
I'm trying to get a model with measured trap parameters to test this
premise. A year or so ago someone offered me a TH-6 model, and I'm trying
to remember who it was. Among other things, I want to see if there is
current "outside" the traps, and maybe some cancellation as a result.
73, Pete Smith N4ZR
n4zr@contesting.com
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