From W4ZV:
> While salt water is definitely good for verticals, but it doesn't
>help horizontally polarized antennas like Yagis. For the low bands
>(160/80) where construction of large Yagis is a mechanical challenge,
>a 4SQ is hard to beat. However for the higher bands, it's difficult
>for a vertical array's gain to compete with the ground gain and
>stacking gain of a Yagi stack. An ideal solution might be a
>combination of both (4SQs for 80/160 and Yagi stacks for 40-10).
>
>73, Bill W4ZV
I can vouch for Bill's statement. For the last three years, I
lived in Key West, Florida, and used vertical antennas for all bands,
160-10m. These verticals were located over salt water, on a dock in the
back yard. For 160 and 80m I used a base loaded, 55ft vertical with one
(1) elevated radial. Over average ground, such an antenna would not be
expected to perform very well at all. Over salt water it was a
different story all together. In three years, I worked more than 200
countries and 38 zones on 160m. 80m performance was better, with all 40
zones worked in one year. Performance on 40 through 160m was
spectacular with just a single radiating vertical element.
On 20m and up, things were more of a challenge. Don't get me wrong
- I did very well on the high bands with simple verticals - but it took
some more finesse to bust through the larger pileups. I found myself
wishing I had the ability to put up a horizontal gain antenna for the
high bands.
While at this QTH, I experimented with a 40m vertical located on
the metal rooftop of my house, about 30ft from the water, and compared
it to the 40m vertical located directly over salt water, 60ft out from
the water's edge. The antenna over salt water out performed the rooftop
antenna in every case, usually by about one S-unit. If you have the
opportunity to operate next to salt water, the closer you can get to
water, the better. Putting it over the salt water works best.
Don't assume you can install a vertical over or next to the salt
water and get away with a single submerged wire as a ground. As W8JI
stated some time ago, salt water is a good conductor but it's no where
as good as copper. There needs to be a decent sized contact patch to
effectively "couple" the antenna to the salt water. I used one or two
elevated radials, placed about 2ft high. AA7JV uses multiple radials or
a piece of metal flashing to increase surface contact, along with a
remote tuner to match the antenna as tidal changes influence antenna
resonance. I feel both methods work equally well, with George's method
adding multi-band capability with a single radiator.
As one final data point, my antennas had a clear shot to Europe, SE
Asia LP, South America, and the Pacific. Performance into these areas
was spectacular. The island on which I lived, about 1/2 mile wide,
blocked the path to the northwest. I did very well in this direction,
although I felt a little weaker than in the other directions. Antennas
in the clear at the end of the dock performed better to the northwest
than antennas closer to land.
This has been and probably will be the best QTH I have ever
operated from. I've since moved out of this location as preparation for
a transfer overseas to Guam, and I already miss the salt water advantage.
73, Dave N2NL/4
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