I've always had real high towers and no restrictions on the amount of
towers I could have. Out in KH6 it is different....one 90 footer on one
plot of land. Since that is a hard and fast rule, the quad loop systems
for 80 meters I've had on the mainland won't be nearly as
effective...according to HFTA. I really can't get enough height for them
to be real barnburners.
So....I've decided to try a four sqaure. Soil here is clay and stays wet
most of the time, plus I have enough room to lay out a good radial system.
The grouind undulates a bit and slopes about ten feet or so in the
direction of the Pacific which is about one mile away. The antenna site
sits at 1100 feet so the slope once it gets off the antenna site is
great...about 1 foot drop for every 5 feet of horizontal.
I've decided to go the Comtek route for the control.
Several questions:
First, any thoughts as how the terrain where the antennas are located will
affect operation? Also, any thoughts on how the big slope from the
antenna
location to the ocean will affect the signal. On HFTA it is a big help on
80 with dipoles etc. but I'm not sure how it will affect a vertical
system.
Second, I have two ways to go on the construction of the verticals. I can
fabricate aluminum full size quarter wave verticals which of course will
provide decent bandwidth, not as good as four towers, but better than wire
verticals. One problem is the location. The closest element would be
about 30 feet away from the tower whcih has seven Yagis stacked on it.
The
other three verticals are about 70-90 feet away(all to one side of the
tower). Guy wires are not the issue (Phillystran), but the tower is. I
have no way to model this thing so it's pure guesswork how much the tower
and other antennas (40-6 meters) will affect the signal.
Last, I could run four ropes from the tower at 84 feet and make wire
verticals in a four square pattern around the tower. To increase
bandwidth
I am planning on running the vertical wires in a "cage". from what I've
read that is the way to increase bandwidth. The problem with this of
course is the proximaty to the tower. All four wires would be within 33
feet of the tower and the seven HF/VHF antennas. So, the vertical system
would "see" the seven antennas and the 90 foot tower. Again it is guess
work on my part as to what effect they would have on the four square. No
guy wires to consider since I am using Philly. The other issue is I am
afraid the 80 meter verticals would screw up 20 meters on my triband
stack.
My gut feeling is the aluminum 1/4 wave verticals located slightly away
from the tower would be less affected by the tower/antnennas. However,
for
ease of construction I really would like to do the vertical wires around
the tower.
This is my first foray into four squares so I would really like some
opinions from guys who have experience in these matters.
Mahaho for the help!
Bill K4XS/KH7XS
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