I would like to solicit opinions on the interactions
between vertical antennas.
I had never seriously tried verticals until rather recently,
but when I took the time to set up a good radial system, I became
very happy with the performance. Now I'm ready to create a
swarm of toothpicks, including some phased arrays.
I'm concerned about the interactions between different
antennas and arrays of antennas. I have several acres, but
not unlimited space. I would hate to go through all of the
construction, only to find disappointing results. In addition, it
is difficult to relocate ground radial systems, so it makes
sense to get it right the first time (well, at least try!).
I'm looking for accumulated wisdom on the rules for how
close you can space verticals without causing undesired interactions.
My antenna library says very little on this subject. I have
done some modeling with EZNEC, but since I write software for
a living, I know better than to trust it. Actually, I'm sure the
software is fine, I just don't trust my ability to model what
is out in the field.
Please mail me any suggestions for avoiding trouble. I
will gather the responses, and can then post them as a group, if
there is interest.
Here is an example. For 160 meters, I am considering
a pair of verticals with 1/2 wavelength physical spacing.
That's about 250 feet between antennas. What can I do in the
middle? A 20 meter 4-square? A 40 meter 4-square? Nothing?
If there is an interaction, who suffers the most?
Do I need to rely exclusively upon physical spacing, or
can I make an antenna somewhat 'invisible' by using stubs, grounding,
or any related techniques?
I should also mention that I am considering ground mounted
verticals and radials - not elevated radials.
Thanks for any suggestions.
Greg Ordy (WB8WWV) (ordy@cadence.com)
--
FAQ on WWW: http://www.contesting.com/topband.html
Submissions: topband@contesting.com
Administrative requests: topband-REQUEST@contesting.com
Problems: owner-topband@contesting.com
|