I honestly didn't know that 10's of thousands of commercial radio stations, as
well as VOA, BBC, NASA, GE, AT&T, Motorola, Harris, Continental and other "non
enlightened" organizations and radio amateurs had gotten it so completely
wrong. Some people actually believe that the 5/8 wave vertical, which is non
resonant, is more effective on some paths than a resonant antenna! And then
there are those nasty multi - element arrays that aren't 50 ohms. And those
poor people running loops, deltas, Sterba Curtains, rhombics and the rest.
We'll have to tell them the truth...they are not getting the results they would
if they had resonant 50 ohm antennas and used 50 ohm coax.
"The Easy Way" by John Hearle, is an enlightening text. Resonance has No
Relationship to antenna efficiency. While it's true that a 50 ohm antenna and a
50 ohm feedline make life easier in certain respects, VERY few Resonant
antennas actually have a 50 ohm impedance. A theoretically perfect dipole
measures 72 ohms at resonance.
Resonant antennas work well. Non resonant antennas can not only work just as
well, but in many cases can exceed the performance of resonant antennas by
several magnitudes. Even when tuned on the "shack side" of the feedline.
Mike
NM7X
Message: 9
Date: Wed, 18 Jan 2006 19:38:38 -0500
From: "Roger Borowski" <K9RB@bellsouth.net>
Subject: Re: [TenTec] What makes the 238 good or any other tuner good?
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Message-ID: <11ee01c61c90$b0789a40$0400a8c0@rb>
Content-Type: text/plain; charset="iso-8859-1"
After more than 45 years of continual hamming on all bands and modes, I can
honestly say that I never have used an antenna tuner and never found any
system that will outperform a resonant antenna fed with coaxial cable, which
I've always used since the early 60's. If the antenna isn't resonant on the
desired frequency of operation, many people think an antenna tuner is the
fix. While an antenna tuner will allow you to use most anything metallic as
a radiator of RF, the most efficient power transfer is to a 50 ohm resonant
load via 50 ohm coaxial feedline. In all cases where an antenna tuner is
used with a coaxial fed antenna, all it does is further complicate a system
with an added piece of equipment that only fools the transmitter into seeing
the match it is looking for, while creating losses in itself and further
losses in the coaxial feedline due to the mismatch that still remains
between the antenna tuner and the antenna. Fortunately I've never been
forced to use anything other than resonant antennas fed with good quality 50
ohm coaxial cable. If you're bound and determined to use open wire feeders
to one of the many non-resonant antenna designs of yesteryear, that would
require an antenna tuner. Why anyone who understands antennas would want to
do that 50-60 years after coaxial cable became common place is beyond my
comprehension. It's an easy chore to adjust antenna lengths for resonance
and where available space doesn't permit, it's also easy to use loading
coils or linear loading configurations on the antenna. If you haven't a clue
as to what I'm saying, pick up a book on antennas, such as the ARRL Antenna
Book and read the entire section on the theory of antennas. As a Ham, you
really need to know this. An antenna tuner is a band aid approach that
allows one to use an inefficient antenna, whatever it may actually be, with
some degree of success. You see 1:1 SWR on the tuner meter and you and your
rig are happy, but in actuality, put another SWR meter after the antenna
tuner and you'll see the real mismatch, why you are generating RFI, and
experiencing far less performance, both transmitting and receiving, than you
could be.
73, -=Rog-K9RB=-
FCC First Class Commercial License first attained in 1967, Ham Radio license
first attained 1961.
A-1 Operator Club, ARRL Life Member, DXCC #1 Honor Roll (350) Mixed, Phone,
CW (since '92) and presently need 11 more on RTTY for H.R. Need (4) more
zones on 160M. for all (9) HF band "Worked All Zones". At present 160 Meter
DXCC - 211 + 36 zones. Former member NIDXA No.Ill.DX Assn., 9th area
incoming QSL bureau sorter for many years, Charter Member Metro DX Club,
Life member / former Trustee W9AA Hamfesters ARC., CP-40 in 1963 at 14 years
of age, former ARRL OO, & NCS, active 160M through V.H.F. / U.H.F. for 45
years. 1st place CQWPX-CW 15M in 1981. 1st place CQWW-CW 40M in both 1980 &
1988. (Ancient history now!) Also KG4RB -GTMO Cuba, Bio and photos available
at www.qrz.com Reply direct to; K9RB@arrl.net
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