In a message dated 96-02-21 17:49:03 EST, you write:
>Have you ever seen actual measured or even calculated numbers for trap
>losses?
>I expect there would be much variation depending on if the trap was
>functioning as a trap (resonant LC with high circulating current) or just as
>a loading coil (like the traps on a tribander when it's being used on 20m
>with no Q multiplier of the current).
Ed --
Thanks for your input and insight. Of course there is the variability
that you mentioned. I have posed the trap loss question to several well
known antenna designers and have never received a definitive answer (varies
with frequency, depends, etc.) but have heard a figure of 4 to 8% loss due to
traps. I would be interested if anyone could enlighten me and the reflector
audience with further insight. That would make a great article for one of
the magazines. It is also difficult to computer model traps so it's not as
easy to analyze multi-band beams as monobanders.
>
>Actually the "5" element C3 is only 2 elements on each band and only uses
>half of the boom on each band so it's gain is not a function of its total
>boom length but only the boom between the driven element and the parasitic
>element.
Correct again but the design and sleeve feed (I've been told) contribute
to greater efficiency than the other conventional trap tribanders mentioned.
Again, a great topic for further study.
Tnx again, Ed, and I look forward to hearing from you again.
73, Steve K7LXC
BTW -- my field is towers not antenna analysis. My perspective is purely
anecdotal as well as what I've installed, used, heard, etc. By definition,
you work on towers, you wind up working on antennas. I've worked on over 100
amateur stations here in the Pacific Northwest.
PS - The article regarding antennas that I mentioned is only available on
hard copy. SASE to Steve Morris, Box 572, Woodinville, WA, 98072, will get
you a copy!
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