In article ,
Gary Schafer wrote:

As Bruce says, "tuners get very lossy with short antennas". But that
is not the only problem with short antennas. The antenna and ground
system become very lossy with short antennas. Below 1/4 wavelength the
radiation resistance of the antenna drops drastically. It can be less
than an ohm. That equates to very high losses. The antenna system in
those cases may be only a few percent efficient.

It is far better to have a longer antenna that gives a much higher
radiation resistance even if it may not be the optimum length as far
as radiation pattern is concerned. If you can't get the power to the
antenna the radiation pattern doesn't much matter. You still won't get
out very well.

On a typical boat the radiation pattern is going to be far from ideal
with whatever length antenna you have due to all the surrounding
objects on the boat.

The difference in radiation patterns between a 1/2 wavelength and 5/8
wavelength antennas are minimal. About the only real difference is the
feed point impedance they present.

As far as antennas greater in length than a quarter wavelength, they
start to produce multiple lobes in the pattern. Which on a boat may
not be a bad thing. As you mention, sometimes higher angles are
desired depending on the distance trying to be covered.

A longer antenna on a typical boat is most always going to be more
efficient than a short antenna even if the longer antenna produces
multiple pattern lobes.

Regards
Gary

Exactly, Doug says he does fairly well on 80 and 40 Meters with
a 23' whip and an autotuner. We take him at his word, but if he
would figure out how to increase that to 50' or 75', there is a GOOD
chance that he would do better, and even in poorer band conditions.
It doesn't take much power or antenna to communicate if the band is
open, to where you want to talk, on the frequency that your using.
Try that if the bands isn't so hot and the time of day is against
you, with a Very Marginal antenna system. Yea, I know most pleasure
boaters have never heard of Marine Frequencies below 4Mhz, but up
here in Alaska we have been using 1.6Mhz and 2.0Mhz - 4Mhz Marine
frequencies for years, and very suscessfully, even on Poor Band Years.
I have used 3261Khz for Maritime Comms for 35 years, and worked my
Fleet Vessels, with 65% completion of Comms, rate on a daily basis.
You will not get that kind of connectitvity, with a 23' antenna,
on your Maritime Mobile Stations. In the "Good Old Days", the previous
generation of Alaskan RadioMen used to work 1630Khz consistantly
every night for intercompany Comms.

Just because SGC says their tuner only needs 23ft of wire, doesn't mean
that you can actually talk to anyone with that type of system. By the
way SGC didn't do the design of that autotuner, themselves, they stole
it from SEA, and didn't even change the "CopyWrite Statement" in the
firmware code. All autotuners on the market today, come from the
original design work of Bill Schillb, an engineer for Motorola MF/HF
Systems, at the time. He worked out the basics of the tuning code and
the hardware design. When he left Motorola and came out west to
Seattle, he landed at Northern Radio for s short while, and while there
passed on the basic technology to Bill Forgey, who was Chief Engineer at
Nothern at the time. Both Bill's left Northern Radio just before it
went under, with Forgey taking the whole Design Team with him, and with
Dick Stephens started SEA. (Stephens Engineering Asscoiates) Dick was
the Chief Engineer at Northern before Bill, and his mentor. Bill Forgey
along with Mark Johnson (an ex Northern Tech) designed the first truely
Marine Radio Autotuner which was the SEA1600, using the basics that Bill
Schillb had imparted, and on which, they improved and expanded. The
first autotuner that had Frequency Memory and Instant Band Switching was
the SEA1612, and the B version is what SGC copied for their 23x series
tuners. Icom, Kenwood, Furuno, and the rest are "Johnnie Come Latelys"
in the world of Marine Autotuner design, and basically they reverse
engineered the SEA design and firmware, for their systems.

I was closely associated with these folks as a Traveling Radio Tech for
Northern Radio, before leaving to become Comm Supt. for the largest
Salmon Canner in Alaska. I count all these folks a close friends, even
after all these years, and also while working the Dark Side (I was a
Field Agent for the FCC for five years) of the industry. I also did a
pile of beta testing over the years for SEA, that included most of their
designs for autotuners. Some of the prototypes are still in use today,
in various places in alaska. I designed and installed the first Marine
Autotuner feeding a Dipole Antenna, and that system is still in use
today. Bill, Mark and I designed and built a 1Kw Maritime Mobile Coast
Station that has 8 Control Points, and uses a SEA1612B Autotuner, and
one of a kind Dipole Antenna for MF/HF Frequencies from 1630Khz
thru 30Mhz at the 150W PEP level, and 1Kw on 4Mhz, 6Mhz, 8Mhz, 12Mhz
16Mhz, 22Mhz Marine Frequencies, using another special Dipole Antenna,
from Morad Electronics. This system is still in use today as well, and
has been around for more than 10 years.

I don't usually "Toot my own horn", but I do have considerable practical
experience in this field, as well as a long history in the industry.



Bruce in alaska onetime Fed, and long time Radioman..........

--
Bruce (semiretired powderman & exFCC Field Inspector for Southeastern Alaska)
add a 2 before @
Bruce Gordon * Debora Gordon R.N. Bruce's Trading Post
P.O. Box EXI Excursion Inlet South
Juneau, Alaska 99850 Excursion Inlet, Alaska 99850
www.btpost.net www.99850.net