[TowerTalk] Why isn't end to end the best method for least interference between two 20 m dipoles?

[Jim Brown]

Jim has correctly identified the problem.  For dipoles to have nulls 
they must be flat, or very close to flat.

For at least 5 years, we've run simultaneous CW and SSB on 80M and 40M 
using dipoles for each band that were approximately colinear and with 
about that spacing for a CQP county expedition. It takes serious radios 
-- we  use K3s driving KPA500s on both bands (500W).

We've run two stations simultaneously on 20, 15, and 10 using 
tri-banders that were approximately con-linear with about 200 ft spacing.

Kip asked about reference material. The ARRL Antenna Book is a great 
place to start. The CD that comes with it includes a stripped-down free 
version of EZNEC that is good enough to model (and study) simple 
antennas like dipoles and verticals. You'll need a more capable version 
that you'll have to pay for to model more complex antennas.

The ON4UN book is also great for antennas for 40, 80, and 160. And there 
are some tutorial things on my website. k9yc.com/publish.htm

73, Jim K9YC

On 3/26/2018 8:31 PM, jimlux wrote:
> Below are the results we did with 2 tuned 20m inverted V dipoles at 35 
> feet, in a test for interference during Field Day.
> The results for Orthogonal was the same, independent of which side was 
> transmitting.