Topband: Inverted L Success Story

[Patrick Dayshaw]

A couple of weeks ago I asked for the collected wisdom
regarding the best way to install radials for a bottom fed
Inverted L strung up over saltwater between the masts of two
sailboats. Thanks for those replies. Based on that info and
further reading on W4RNL's excellent Web site
(http://www.cebik.com/radio.html) I decided to follow a
slightly different route than originally proposed. The
antenna selected was a 160M Inverted L top-fed with 300 ohm
twin lead and suspended over saltwater. I also devised a
test for it.

I decided to run a comparison between my home station
antennas and the *Saltwater Top-Fed Inverted L* by working
the 160 ARRL Contest from home on the first night and
portable from the boat on the second night (The location
change was duly noted in my submitted log.) The antennas at
the home location are a HF2V 36 ft vertical with 160 coil
over 1200 ft of radials or a 125' bottom-fed inverted over
the same radials. I can also  short the open wire feed line
of the 80M dipole and feed it as a long wire. Those antennas
represent what I can get on my small city lot, nothing more.

On Friday here in the US Northwest conditions were fair and
I could hear, over the course of the night, stations from
much of the country. However, few could hear me. Stations in
6 land that were S9+ couldn't hear me - not even a ??. The
result of the first nights work was a miserable 39 Q's.
Something needed to change.

On Saturday morning after a couple hours sleep I
disassembled the station and headed for the boat. By 3 p.m.
I had everything setup on the boat and the antenna erected.
It loaded up effortlessly. Once dark settled in it became
clear that I had a lower noise level on receive as well.
This could be fun!

The antenna was installed with the 134 ft. horizontal wire
50 feet above saltwater supported at both ends by the 50+
foot masts of two sailboats. The 134 ft long *vertical* leg
dropped down 45 ft. and then turned and ran parallel to the
water about 4-6 feet above it for its length. The two
horizontal sections are 180 degrees to each other. There is
nothing but saltwater and a small amount of floating wooden
dock under the any of the antenna. It just *hangs in space*
over the water. The dock location puts the feed point about
400 ft from shore (at low tide). The antenna is fed with 300
ohm twinlead (I'll use 450 ladder next time). Physically the
feed point is actually suspended out over the water away
from the boat. I led the feed line away well clear of the my
boats mast and its rigging. The antenna is matched by a
balanced-balanced (twin roller inductor) matchbox. 

Conditions on Saturday night were definitely not as good as
Friday but the new antenna played very well. The difference
was astounding actually. With one or two exceptions I worked
everything I could hear and I was hearing a lot better as
well. Rather than me calling endlessly I got answers on the
first call. CQ became something I could actually use and I
was answered by stations that were clearly copying me well
but themselves were near my noise level. While compared to
standards in other sections of the country the 102 Q's I
made on the 2nd night for a 141 total won't seem like much.
However, here in the WWA section last year's Low Power
winner only had 257 total Q's for the entire contest. The 39
vs. 102 Q number (and the 102 was in poorer conditions)
really says it all.

Now that I have the taste for what a reasonably sized
antenna over saltwater will do, expect to see me again. I've
already found the perfect spot to anchor the boat that will
allow me to fly a 1/4 wave vertical via balloon in a small
protected harbor. If the weather doesn't co-operate for the
balloon effort then I'll be back with the *Saltwater Top-Fed
Inverted L*. 

Now all I need are receive antennas. Anybody done any
*floating beverage* installations?


73 
Patrick 
WA7VNI