Tom is correct when he wonders about these posts.
SWR close to 50-ohms, and wide antenna bandwidth, is not an indication of
radiation efficiency. A lobe in a particular direction is only meaningful
in terms of whether or not that is a desired direction. You can gimmick any
antenna to exhibit a perfect match to whatever feedline you are using.
Theoretical efficiency and actual results are entirely separate matters.
With a theoretically perfect 1/4-wave vertical and ground system you will
not have a perfect 50-ohm match. If you fiddle around and somehow get a
50-ohm feed impedance with no matching intervention then you have somehow
reduced efficiency and increased losses. Nevertheless, the feel-good effect
is powerful.
What a lot of hams forget is that any piece of wire or tubing will have some
certain feedpoint impedance at a given frequency. You might hook a feedline
to a gutter and get a 50-ohm match at 7.050MHz. This is guaranteed to not
be an efficient antenna at almost any level of consideration. Yet, if you
can make QSOs with it, and you have no other alternatives, and if you are
reasonably happy, then what more do you need?
Over-engineering is a pervasive and very time consuming tendency.
Over time (a long time) it might produce results, but if you waffle about
getting on the air because your feedpoint impedance is a few ohms off of
whatever you want then you will miss most of the fun and a lot of QSOs.
------------------- Wes Attaway (N5WA) ------------------
1138 Waters Edge Circle, Shreveport, LA 71106
318-797-4972 (Office) - 318-393-3289 (Cell)
Computer Consulting and Forensics
-------------- EnCase Certified Examiner ---------------
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Tom Osborne
Sent: Thursday, May 12, 2011 2:23 PM
To: Towertalk
Subject: [TowerTalk] Vertical with 1 radial
Blank
Hi All
In the past 2 months, I have seen two different articles in ARRL
publications that say a vertical with 1 radial has gain in the direction of
the radial. One said 3 db. Evidently Eznec confirmed this.
Why the heck do I bother putting down all those radials under my verticals??
According to one article, 1 radial is best because it gives the antenna a
real wide bandwitch, SWR is close to 50 ohms, and has gain in the direction
of the radial. Seems like those symptoms would give loss not gain.
Is this true, or is the ARRL just publishing anything now? Sure is
different from anything I've ever known about verticals.
Seems like I should be able to put up an antenna with 1 radial on my rotor
and I could point it just like a beam. Fill me in. 73
Tom W7WHY
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