>From what I've read in materials from the ARRL is that anything under a
2.0:1 SWR is great.
However, anything under a 5.0:1 SWR is negligible loss at HF frequencies.
Fighting it lower is a pursuit of diminishing returns.
Feed your antennas with ladder line and a tuner or put the balun as close to
the antenna as possible to reduce transmission line losses.
Resonance is overrated. You want your radio to run full power into what it
sees as an SWR under 2.0:1.
On the other side of the tuner or balun it really doesn't matter if it's
8:1, 15:1 or whatever because the losses are RF radiation losses and not
losses as heat in the coax.
What you want to prevent is a high SWR (> 5:1) on coaxial cable. On ladder
line it doesn't matter.
ARRL members can read this article that debunks the myths of SWR and
resonance:
www.arrl.org/members-only/tis/info/pdf/Reflect.pdf
------------------------------
Message: 4
Date: Sun, 09 Nov 2008 10:07:53 -0500
From: Blair S Balden <blair.balden@wmich.edu>
Subject: [TowerTalk] wire antenna question
To: "towertalk@contesting.com" <towertalk@contesting.com>
Message-ID: <3af18bee3559.4916b679@wmich.edu>
Content-Type: text/plain; charset=us-ascii
Hello antenna gurus,
I have a question regarding wire dipoles that's been bothering me. I'm sure
someone on towertalk can help. Here it is:
When I put up dipoles, whether they be "straight" or inverted V's, I've
always started out with the wire a little longer than the formula length of
468/f. Then I've trimmed for as close to a 1:1 match as I can get to my
50-ohm coax, as indicated by my SWR meter. I can usually get a 1:1 SWR.
These antennas usually work very well, but I realize that a resonant dipole
will not have exactly 50 ohms resistance. So, I must be cutting these
antenna somewhat off resonance. I also realize that a mismatch at the
antenna (SWR of greater than 1) results in loss.
What I'm not sure about is whether it would be better to get the antenna
resonant at the desired frequency and accept the mismatch, or whether I
should continue to go for the best SWR (minimizing losses due to the
mismatch).
BTW, my rig does not have an internal antenna tuner, and I am currently
without an external tuner for it. So, I'm running it without a tuner (if
this matters). Also, I have not been using any kind of matching device at
the feedpoint, just direct connection from the coax connectors to the wires.
If someone on here can give me some insight as to whether I should try to go
for resonance instead of low SWR, please respond. I would truly appreciate
any help with the question.
73,
Blair NP2F
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