[CQ-Contest] Contest QTH, hilltop or seaside?

[Jim Breakall]

Hello All,

This is an interesting topic for sure and I have experienced both hills 
and ocean with the volcano 300 foot high
hilltop at my contest station built near Arecibo, Puerto Rico where we 
have used Angel's callsign,
WP3R.  The hill is the highest one in that part of north central Puerto 
Rico and you can see the ocean
for almost 180 degrees to the north about 8 miles away.  It is shaped 
like a cone with only about 100 feet
flat on top and drops off very sharply in all directions.  I always had 
my eye on this hilltop ever since
going to the Arecibo Observatory back in the 70s and was lucky to be 
able to purchase the farm there in
the 90s and build the contest station with the help of Nathan, NW3Z, 
Angel, WP3R, and Pedro, NP4A,
and many others.  The antenna tower there is only 60 feet high and the 
10m OWA Yagi is only up 30ft.
I think some of you may have heard the WP3R signal during sweepstakes 
some years ago on 10m with just
a single 24 ft boom 6 element 10m Yagi up 30 ft.  It is pretty amazing 
to hear signals from this hilltop.

Back in the early 90s, I had a project with the US Navy to measure the 
effects of a dipole and monopole
in front of a hill, on top of a hill, and behind a hill for various 
frequencies at HF and use a helicopter
trailing a measurement system to get the patterns for each of the 
cases.  We then used a technique
that is mainly used at microwaves and higher to model the terrain called 
the Geometrical Theory of
Diffraction (GTD) / Uniform Theory of Diffraction (UTD).  We used it at 
HF and used various plates for
2D modeling including the ground parameters and also later even used it 
with triangles to do 3D modeling
of the hill, etc.  The agreement between the measurements and the 
modeling were stunning and we
reported on this work which was the first of its kind in the IEEE 
Transactions on Antennas and Propagation.
At the same time, I also communicated these results and the techniques 
to my good friends Brian Beezley,
K6STI, and Dean Straw, N6BV, who both were extremely interested in 
making this available to Ham Radio.
The rest is history with Brian's TA software and Dean's HFTA, etc. This 
made me so happy to be able to
take something that was research at the time for the military and be 
able to transition all of this to
the Ham Radio community.  It was fortunate to have such clever 
programmers as Brian and Dean put
together all of this software and their work is remarkable.

Before I ever built the contest station in Puerto Rico, another friend, 
Bruce, WA3PTU, and I went to Puerto Rico
in the late 70s and did a multi-op sweepstakes phone with just a 5BTV 
vertical that was placed right above the
water some 10 feet past the beach on a stake.  It was temporary and 
Bruce being a diver installed a few radials
right into the saltwater and the ocean floor there.  Since it was only 
for the weekend, we didn't care how long
it would last.  Wow !!!!  The signals were fantastic since we were on 
the north central coast of KP4.  We kept getting
called from DX stations in SE Asia, India, Japan, etc. telling us how 
loud the signals were.  There clearly is some
amazing enhancement as others have reported with signals when an antenna 
is placed right at the boundary
between land and the sea.  I remember once being told by my old friend 
Sam Harris, W1FZJ (SK) at Arecibo
that he feels his signal dropped some 20 dB when he moved from the beach 
to further inland.  Someday, I will
try to model this effect since there clearly is some interesting 
diffraction effects caused by that boundary.
Of course, the lower angle radiation is so much enhanced also.  I will 
never forget that sweepstakes ever with
all the DX that kept calling us and we telling them we were in a USA 
only contest....haha.

I put in a few plots from TA which I still use especially for 
demonstrating diffraction effects since it works very fast in
real time to interactively make changes.  I actually put in the same 
GTD/UTD model of the original hill for the Navy
work that was near Provo, Utah.  I put a Hy-Gain 105CA 10m 5 element 
Yagi at 34 ft, 53 ft, and 103 feet on top
of the 120 ft hill above the flat desert below.  The gain at 34 feet is 
amazing and gets to almost 20 dBi which would
take a nice stack of Yagis to do on flat ground at a very high height 
for the same gain at that low of an angle.  We have
such a stack of four 7 element OWA 10m Yagis (top 180 ft) at K3CR that 
just gets a little more gain as this at a low angle.  I also put
in a photo of what the same 105CA Yagi would do at 61 ft on flat ground 
too.  At the higher heights on top of the hill,
the gain is never close to 20 dBi and there are many peaks and nulls 
which is not very good at all.  Dave Leeson, W6NL,
knows all of this very well since he has a mountain top QTH near Montery 
Bay, CA and has written extensively on using the foreground
and low heights to enhance his signal at lower angles.

Happy New Year to all and hope you can see the photos.

I don't submit much to CQ Contest but do a lot of reading....haha. I 
hope this gets there.

73  Jim  WA3FET (K3CR, KC3R, WP3R)




-- 
James K. Breakall
Professor, Electrical Engineering

225 Electrical Engineering East
Penn State University
University Park, PA 16802

Tel: 814-865-2228
Fax: 814-863-8457
Cell: 814-883-6521