[TowerTalk] Greyline Performance antennas

[Jim Brown]

On 10/17/2020 1:24 PM, Kim Elmore wrote:
> Maybe I should have said "... making sure it has a good CM choke," 
> especially since you've taught us how to make them! Even if the feed is 
> in the center (it could be if the transmission line is run up the bottom 
> half) it still won't be balanced. A CM choke is always needed. I've 
> become convinced that balanced antennas make analysis much easier (even 
> possible) but that in the real world, there aren't any.  I have no idea 
> what the electrical length is for 6 m or even 10 m, so the low 
> radiation-angle assumption might be invalid on those bands.

Here are slides for a talk I gave on the Pacificon Antenna Forum several 
years ago on an 80M vertical dipole for our 7QP and CQP expeditions, 
based on N6BT's design ideas. Yes, it does need a serious choke were the 
coax feeds up through the tubing to the feedpoint.

http://k9yc.com/80M-FDVertical.pdf

Testing it in Glen's pasture showed it to significantly outperform an 
inverted Vee with the center at 46 ft, but mechanical issues with the 
design caused us to abandon it after modeling and building several 
alternative designs.

73, Jim K9YC