. A couple other guys who know what they're talking about are also
recommending that same arrangement. 50 ohms on the cable and 50 ohms on the
antenna --- perfect. No need for a matching device, I like it. But aren't
dipole-like configurations supposed to present 73 ohms of load? Why is a
1/4 wave groundplane only 50 ohms?

The simplest ground-plane-style antenna has its radials sticking out
sideways. It's a monopole. The actual radiator is only half as long
as a dipole, and thus has only half as much radiation resistance, and
the feedpoint impedance is only half as much as that of a dipole.
It's on the order of 35 ohms or so.

If you bend the radials until they point straight down, you've got a
center-fed dipole with the feedline running up the center. Feedpoint
impedance is somewhere around 70 ohms.

Feedpoint resistance of anywhere from 35 to 70 ohms are available via
the obvious compromise - just bend the radials down less (for lower
resistances) or more (for higher resistances).

In most installations, radials bent downwards at an angle of about 45
degrees result in a 50-ohm resonant feedpoint resistance.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
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