TopBand: Shunt & Gamma Feed for Tower

[Craig Clark]

At 09:02 AM 11/12/96 -0500, you wrote:
>     This is primarily for Fred, K1VR, but all are welcome.
>     
>     The original shunt feed article by John True, W4OQ and later N4BA, 
>     from Ham Radio, May 1975, is still very up to date.  The omega match 
>     will work fine, sometimes in reverse direction.  Original shows a 
>     series capacitor and a shunt capacitor across the coax feed.  
>     Sometimes the shunt capacitor needs to be a smaller value on the other 
>     side of the series cap.  That is between the bottom of the gamma rod 
>     and ground.
>     
>     Gary Breed, K9AY, wrote an update on using two wires in parallel to 
>     broaden the match bandwidth in an issue of the Low Band Monitor by 
>     Lance Johnson Digital Graphics, K0CS is the editor.
>    
The True article in HR is a classic. I recommend all looking to build a
shunt feed
antenna  read it several times.

>From Oct 75 QST, W1FB and W5RTQ have artilces on building shunt fed
antennas. Both are quite helpful.  Dec 77 CQ, W5JJ on verticals. And, from
ARRL Ant Comp Vol #2, page 36, K5YNR on unipole antennas.

I feed the grounded antenna at the top in a uni-pole configuration, with a
large driven element (same size as the 25.) I use a step-up L network
(series L, parallel C) and get good performance.

GL and cu on 160!

Craig


 
			Craig Clark
		     soon to be ex-NX1G
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