I suppose I should offer some comments on my experiences operating
from a coastal Maine QTH.
My contest station is on an island about 5 miles offshore from
Portland, ME. The island is 3 miles long, about a half-mile wide, and
lies along a line that runs pretty much NE-SW. My house is at the NE
end of the island. I do not own the land down to the water, so my
antennas are not right on the beach.
My 160 antenna is a two-element array of quarter-wave-spaced
inverted-Ls, each about 60 feet vertical and the rest sloping up to
the 90-foot point on my tower. The center of the array is about 300
feet from a small cliff overlooking the water, and about 400 feet from
the water to the east and south. The cliff is 20-30 feet high,
depending on the tides, which are about10 feet in Casco Bay.
Each vertical has about 30 radials on the ground, not very symmetrical
due to the property lines, and varying in length from .1 to .25
wavelengths. I stopped adding radials when the feedpoint impedance of
each element stopped changing significantly. The soil is forest muck,
and ranges from 0 to 3 feet of depth before hitting rock. The system
is fed with a Comtek 2-element phasing box, with the addition of an
extra option of 180-degree phasing to yield a bidirectional end-fire
pattern.
I have had good results with this antenna system and location. I am
usually among the first and often the first one through pileups for
DX.
The Reverse Beacon Network data shows that my 160M signal stacks up
well against other Northeast U.S. stations, but is not the
rock-crushing 10s-of-dB louder that fans of beachfront locations would
suggest. Maybe if I owned the property across the street and could put
up the same array with the front element in the water I would get that
magic 10s-of-dB enhancement. But I don't, and as has been pointed out,
maintenance of antennas right on the water is problematic, so being
"close" to the water seems to be sufficient.
In the 2013 CQ160 contest, my signal in Europe was about equal to W2GD
and K3ZM, (300 and 400 miles south of me and right on the water), and
a few dB below VY2ZM (450 miles closer to Europe).
In previous contests, K8PO, also in Maine, but 10 miles inland and
about 50 miles north of my QTH has a signal that is usually comparable
to mine, using a single (real) vertical and a lot more (and longer)
radials. He is louder than I am to the West and SW, since I have a bit
of a hill behind me and his terrain is flat over a pond in that
direction.
I do have one secret weapon, and that is my receiving capability. I
run a two-wire Beverage back in the woods on a friendly neighbor's
land (starting about 700 feet from the water, and running over mostly
rocky soil) during the winter months. I very often get reports from DX
stations after contests that I was the only USA station that could
copy them, and from well-equipped NE USA stations telling me that they
could not hear most of the stations I was working.
I have a wire 4-square for 80 at about the same distance from the
water as the 160 array (which would make it twice as far back in
wavelengths), and it also works quite well. Maybe it would work better
right on the water, but it works well enough.
On 20-10, I have some stacked Yagis, and as many commenters have
noted, the only benefits to a salt-water foreground for
horizontally-polarized antennas are a uniform surface in the Fresnel
zone and lack of obstructions. I agree with them, but those effects
can be significant.
A few years ago, K0DQ ran an exhaustive analysis of RBN data after the
CQWW CW contest, which he operated from the QTH of WW1WW. That
station, in central NH about 75 miles inland, is on a hilltop with a
very nice sloping foreground towards Europe, and stacks of high
antennas. On 20-10M, my Maine station had a 1-2dB advantage over the
much bigger antennas at the WW1WW station. That could be due to the
antennas being at heights better matched to the optimum takeoff angles
that weekend. I have often joked that the tides must have been right
that weekend (and conversely, any time I lose a contest, I blame it on
the tides).
Modeling the 20-10M Yagis with and without the presence of the cliff
shows some interesting effects. The higher-angle lobes are no
different in the two cases, since the lower parts of the free-space
vertical pattern hit the same (average soil) medium. However, the
lower-angle lobes are pulled lower by the cliff (since the first
reflection point is further away), and the higher efficiency of the
salt water seems to add a dB or so to those lower-angle lobes in the
far-field pattern in EZNEC.
I suspect that for horizontal antennas, a nice sloping foreground
towards the ocean would be terrific, even if it is a mile away. I have
not yet figured out how to model a sloping foreground in EZNEC, so
getting the heights right for the desired angles may require some
experimentation. For verticals, getting closer to the water (even if
not right ON the water) works quite well, and is a good tradeoff
between performance and maintainability. A 160M vertical a mile inland
may not be the killer antenna that it would be at the beach, but for
W2RE and Remote Ham Radio's purposes, it would be a huge step up for
an operator in W6 or even W9 who wants to get a taste of East Coast
Top Band operation. Ray and I had this discussion in person last week
at the Maine State Convention last weekend.
Maine is a good place for contesting most of the time and the low
bands are a lot of fun there. At the top of the sunspot cycle, being a
little closer to Europe and getting sunrise a bit earlier makes a
difference. But at the bottom of the sunspot cycle, it can be
frustrating to hear stations 50 miles south running stations on 10 or
15 meters when Maine is shut out. And maintaining a station in coastal
Maine is a constant challenge, requiring a lot of attention to detail
to contend with wind, ice, and salt corrosion.
73,
Doug K1DG
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