[Antennas] Building A Coil

Sun Aug 24 22:01:35 EDT 2008

End fed 1/4ave?? Without a GROUND PLANE OR counterpoise radial system under
it, forget it radiating any better!!! ANY SHORT antenna requires LOW gnd
losses to radiate above 10%..
Forget trying a 1/2wave and put a GROUND under the antenna...that's the ONLY
way you will get improvement and more radiation...anything else is pi..ing
in the wind....Sorry...
ALSO top loading is better than anything else on the vertical side to raise
radiation resistance and improve radiation..but the gnd has to be there
1st...NO, doing 1/2wave electrically will NOT work...(only way it will is
raise the vertical to minimum 1/4wl physical height and then add 1/4wave
electrically through loading or coils...but WHY?? 1/4 wave is easy to match
and offers decent radiation)
"YOU CANNA CHANGE THE LAWS OF PHYSICS" (Capt. Montgomery Scott, Engineering
Dept, USS Enterprise...Scifi or not, ITS RIGHT!!)
Chris
WB5ITT
Lamar University EE, 1976-1981
-----Original Message-----
From: antennas-bounces at mailman.qth.net
[mailto:antennas-bounces at mailman.qth.net] On Behalf Of Mark
Sent: Sunday, August 24, 2008 6:19 PM
To: Antenna Mailing List :>
Subject: [Antennas] Building A Coil
Hi
 I have an idea on how to improve my mobile antenna that I am using on a
portable tripod. I need some help to make my idea come to life however. My 
antenna is a 75 meter mobile and it presumably acts as an end fed quarter 
wave. I am looking for a coil that I could mount between the feed point of 
the antenna and the mount. It would need the appropriate 3/8 threaded 
adapters at each end. This coil needs to act as a quarter wave resonator. 
This will bring the antenna to a total of a half wave. Does any one know if 
such a coil is made on the market or if there is some one I could higher to 
build one like this?
 Thank you for your help.
God bless,
Mark