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Re: [TowerTalk] rhombic antenna

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Subject: Re: [TowerTalk] rhombic antenna
From: "W4ZW" <>
Date: Sun, 30 Jul 2006 18:09:59 -0400
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I had one up for several years.  I moved into deed restricted area, but
forced the developer to pre-approve engineering drawings and installation of
a 76' crack-up in my "back yard" as a condition of buying three lots (about
3 acres each) and building one house on it with perimeter landscaping all
the way around.  When I spoke with the neighbors (not many because it was
still just being developed) they were upset that I was going to put up
yagi's that could be seen when extended.  I opted for good neighbors, and
put up a rhombic since the lot was almost in an irregular diamond shape.
The rhombic was about 70' high and about 380' on each leg and was supported
at either end by a guyed 70' combination of 50' Rohn 25 and a 20' steel mast
which were painted green camo. The sides were supported by various lines
strung to the very tall slash pines in the yard.  I experimented with it
both open and terminated and fed it with open line.  When open, I could work
ZL/VK as well as my usual eastern European friends.  It also seemed to have
some extraneous lobes off the center that exhibited gain.

My experience is anecdotal and comparisons were made to a butternut vertical
and various dipoles, but it was a killer antenna in very narrow beam widths.
There were places in Eastern Europe I could work with regularity with more
often than not "you're the strongest W or only W  on the band."  But out of
that narrow piece of geography, I seemed  invisible.  I could switch to the
vertical or the dipole and signals blossomed out of the noise, but the
contact with the Rhombic practically disappeared.  It was about the same as
switching off the amp according to the guys who tolerated my testing.  I did
hang a Cushcraft A4S on the nearer tower and immediately regretted not going
with my original tower/yagi's  concept.  

Final analysis:  great antenna in very narrow beam widths but darned
difficult to turn.  Go with a yagi, you'll have more fun.  I also
experimented with a traveling wave antenna for transmitting that went up 70'
out 670' and down 70'  to large non-inductive resistors into a ground field.
It was also very directive but had wider (more useable) lobes than the
rhombic.  Both of these antennas induced  lightning snap, crackle, and pops
every time the Orlando T-storms started marching near.   I could hear and
see the sparks jumping across the feed lines, and finally got tired of
replacing the feed lines and gas discharge units and took the whole thing
down.  This was about the time I moved to Europe for six years and enjoyed a
return to yagi's.

My opinion is that phased verticals would be a better option if yagi's are
out of the question.

My 2 cents.

Jon Hamlet,  W4ZW
Casey Key Island, Florida
"A little piece of paradise in the Gulf of Mexico"


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