[TowerTalk] vertical dipole

[Jim Jarvis]

Hi Tim,

You got it exactly!  

A vertical dipole avoids the IR losses in the ground, but not
the absorption and brewster angle effects at first reflection.
They're outside your control, anyway.

If the radials were running almost vertical, within a few feet of 
the feedline, they'd decouple the feeder to a substantial degree...
and it would start to look like a vertical dipole.  Probably need
a common-mode choke on the outside of the feedline, below the
radials, though.  

I'm going to try this for 80 this summer...run the feeder along 
the tree, and four radials down the sides of the 3'diameter oak...
and the upper half of the dipole horizontally.  So it's a top-fed 
halfwave inverted ell dipole.  

Working on a dual band version for 30 & 40, in another tree.
The real problem is how to get something meaningful on 160, however.
Stealth antennas in suburbia! :) 

n2ea
jimjarvis at ieee.org