On Oct 25, 8:31*pm, John Ferrell wrote:
It looks like I am going to have the resources to install a second
antenna tower. I never thought it would work out this way so I have
not planned it as I put other things in place.

The question is: How close is too close?



I would appreciate any thoughts and especially experience.

John Ferrell W8CCW

I have used for the past three years a 40M vertical and and 80M loop.
I use the 40M vertical for 40 and 15M and the loop as a multiband
80-10M. The pair worked great for me at my location. The loop WAS
supported by four 25-32ft trees. When I tried to improve the system
by raising all the corners of the loop to 32 ft, by using some 32 ft
lengths of metal tubing I pieced together, my 40M vertical did not
seem to work as well. There was not a big difference in the 80-10M
loop it worked fine both setups from what I could tell. Note that I
never used the loop for transmit on 40M as the vertical worked great
and my reason to increase height was not to improve performance of the
loop but for the wire to clear the tops of the trees and not get
tangled as often.
With the metal tubing supporting the corners of the loop it seemed
like the 40Mvertical was a totally different antenna(not as good of
one). As well, resonance the 40M vertical shifted slightly. As my
antenna is in a fairly dense wooded area when it rain heavily or we
have freezing precipitation I also see a similar effect.
The metal vertical support for the corner of the loop was about 37ft
from the base of the 40M vertical. I used this setup over a period of
time and when I removed the metal support tubing , resonance shifted
back on the 40M vertical and it seem to play as it did before , like
the on I home brewed originally.
I'm sure I could have used decoupling techniques so the 40M radiator
did not "see" the vertical elements in close proximity but never did
put the tubing back up when it came down, used much better wire that
didn't tangle.
So how close is to close? I think 37ft was too close for a 40M
vertical in proximity to a 32ft support mast for optimum performance
for the vertical, but if its a second tower I'm sure the gain will be
much better than losses of coupling especially if it means a new 3
element 40Meter monobander as the antenna on the "new tower". I have
ON4UN's Low Band DXing, which is awesome and a must have for all
Ham's, John I believe uses or has used a 160M vertical in the center
of a four square, and uses decoupling techniques between the two. If
there is an issue with the closeness of the two, decouple at that
point. Hope this helps.