On Sun, 25 Dec 2005 06:32:53 -0500, Scott in Baltimore
wrote:

+Vinnie S. wrote:
+ On Sat, 24 Dec 2005 16:27:10 GMT, "GHB" wrote:
+
+
+The radio shack GP w/ horizontal radial worked but had higher SWR than the
+starduster with it's drooping radials. Have you considered using an old
+102" SS whip mounted on drooping radials that you would construct? The
+drooping radials would allow for an almost perfect 1:1 SWR match but include
+the spring since the vertical element needs to be 108" long. This antenna
+would essentialy be a starduster.
+
+
+
+ Can he make a longer radiating element and put the radials at 90 degrees? That
+ woulb be easier than drooping the radials.
+
+ Vinnie S.
+
+Resonance occurs due to the physical lenght of the radiator plus any
+coils minus any capacitance. The electrical match is due to the feedpoint
+impedance. An odd quarterwave has a low impedance. Anything else has a
+higher impedance. To match 50 ohm unbalanced coax to various types of
+antennas, baluns and beta/delta/gamma matches were created.
+
+Some antenna designs have the radials at 90 degrees because that is
+where the designer put them to work properly with their design.
*******

The only time an antenna is resonant is when the feed impendance is
real. That is when the imaginary portion of the antenna is zero.
Therefore the feed point impendance is R + j0. Resonance does not have
to occur at 50 + j0 Ohms.

There are an infinite solution to where the magnitude of the impedance
is equal to a magnitude of 50 Ohms.


james