On Sat, 24 Dec 2005 18:26:15 GMT, james wrote:

On Fri, 23 Dec 2005 19:30:25 -0500, Scott in Baltimore
wrote:

+ I don't think so, only because I have seen flat ground planes. My Starduster
+ were at a sharp angle. Maybe Scott can knows better. I would think the flat or
+ GP at 90 degrees to the center conductor is fine.
+
+Straight radials would create a 30 ohm antenna.
+45 degree droops create about 50 ohms.
+
+There shouldn't be any current flowing down the outside of the
+shield with a groundplane, so you won't need a balun,
+unlike a dipole that requires equal and opposite phases.
+If you try to feed a dipole with coax, the outer shield
+becomes part of the antenna system, causing high SWR readings,
+(even if the SWR is low), RF interference and degraded performance.
******

At 30 Ohms you will need some matching network to cancel the reactive
portion out and rasie the radiation resistance of the antenna up to
that of 50 Ohms. I would not reccomend direct coax attachment even to
a 1/4 lambda ground plane antenna.

james

So what reactive component does a 1/4 wave monopole have? How much
loss do I have on my 40 meter 1/4 wave vertical fed directly with RG-8
coax? Should I put a coil or capacitor at the feedpoint of my
vertical?