[Top] [All Lists]

[antennaware] Efficiency and losses

To: <>
Subject: [antennaware] Efficiency and losses
From: (L. B. Cebik)
Date: Thu, 24 Sep 1998 21:53:41 -0400 (EDT)
Traps can be modeled directly if one has access to a value of Q for the
coil.  Roger Cox of HyGain once published values on one list for the traps
they use for 21 and 28 MHz, along with their resonant frequencies and
inductances, so one can do all the modeling needed.

Rules of thumb for trap losses are not too reliable, since the losses of a
trap vary from band to band, since the effective Q of the trap changes
from band to band.  One has to convert the series R and L into parallel
values for use with the C that makes up the parallel trap circuit.  As you
change frequency, the equivalent parallel R will change, since the net
reactance of thre trap will change with frequency.  There are some notes
on basic calcuations for this at my site.

However, even if one has values for a trap from one maker, it is likely
not safe to use the same values for a different maker using traps.  Same
goes for loading coils.  Also, I am uncertain of the effect on Q of
spiders and other critters who typical nest in traps.

Hope this is useful.



L. B. Cebik, W4RNL         /\  /\     *   /  /    /    (Off)(423) 974-7215
1434 High Mesa Drive      /  \/  \/\     ----/\---     (Hm) (423) 938-6335
Knoxville, Tennessee     /\   \   \ \   /  / || /      (FAX)(423) 974-3509
37938-4443     USA      /  \   \   \ \       ||    

FAQ on WWW:     
Administrative requests:

<Prev in Thread] Current Thread [Next in Thread>