|To:||Jan Erik Holm <firstname.lastname@example.org>|
|Subject:||Re: [TowerTalk] 4 SQ arrays|
|From:||Jim Lux <email@example.com>|
|Date:||Fri, 19 Nov 2004 11:00:52 -0800|
At 04:51 PM 11/19/2004 +0100, Jan Erik Holm wrote:
Now I see my error. I checked at .35 wl spacing and that will give about .5 wl on the diagonal. Don´t know why I wrote 1.5 wl and 2 wl below, my fingers are to fast for my brain. Anyway, at .35 spaceing the F/B doesn´t seem to get better, what I wrote below will happen.
Tiny fractions of a dB difference in forward gain (11.56 vs 12.04) Big difference in F/R (20+ vs 10-15 dB)
I suspect that the "real" performance will be much more affected by the changed mutual coupling with the elements at a different spacing. More to the point, the different impedances will affect what phases that hybrid really produces (and, if you're 0.25 WL from the center on the diagonal, that means your feedline must be somewhat longer than the nominal .25 WL called out in the Comtek instructions, so that's yet another factor that would have to be considered.)
I haven't tried it, but it should be possible to model the Comtek box (or any "Collins hybrid") in NEC with NT and/or LD cards. Then, you'd get all the interactions properly modeled.
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA.
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