Hi Tom,

K7ITM wrote:

Amen, bro. Another advantage of the ground plane: the radials
decouple the feedline from the antenna. . .

Here's a fun experiment with EZNEC.

1. Open the VHFGP.EZ example file. Click View Ant to open the View
Antenna display. In the View Antenna display control section, click
Center Ant Image so you can see the antenna better.
2. Add the following wi

End 1: 0, 0, 5 (wavelengths)
End 2: 0, 0, 4.727 (wavelengths)
Diameter: 0.25 (inches)
Segments: 6

This represents the outside of a feedline connected to the feedpoint.
3. Click the Currents button. Look at the display and, in the Currents
box, compare the current on the outside of the "feedline" (Wire 6,
Segment 1) to the main radiator current (Wire 5, Segment 1).
4. Change Plot Type to Elevation. Click FF Plot to see the 2D elevation
pattern.
5. Reconsider the statement about decoupling. . .

This is admittedly contrived to show a particularly extreme case. But
try different lengths of "feedline" either open or connected to ground
and you'll find other cases where the feedline current is high and the
pattern distorted. You'll also find cases where inserting a "balun"
(high impedance load) in the "feedline" will actually increase the
feedline current due to changing the current distribution to a value
more favorable for the particular feedline length.

Roy Lewallen, W7EL