G'day all,
----- Original Message -----
From: "Phil & Ann Duff" <na4m@arrl.net>
To: <topband@contesting.com>
Sent: Friday, September 16, 2005 4:11 PM
Subject: Re: Topband: Tuning elevated radials
| The KJ6GR article referenced "HF Antennas for all Locations" by Les
| Moxon G6XN where Moxon discusses radial current imbalance and
| recommends radials less than .25 wl.
|
| Among the summary conclusions reached by K5IU
| .25 wl is worst possible radial length for current imbalance in
| elevated radials.
| .125 wl radials fed thru a common radial inductor have much less
| current imbalance vs .25 wl radials with no significant reduction in
bandwidth.
I was going to refer to the G6XN recommendation.
I have used this technique on my 30M vertical. The vertical element is 30
feet long with the base 3 feet from the ground. Two gull wing radials
then rise at 45 degrees to a height of 6 feet, then horizontal to the end
supports. The radials are less than the length required to naturally
resonate the vertical and connected to a common loading coil then the to
coax as normal and a large coax choke. The off centre feed caused by the
oversize vertical element gives me a pretty good match to 50 ohms, exactly
as predicted by modelling. I don't have any other 30M antenna to compare
it with, however, it does a good job with the DX.
Apologies for the high frequency reference.
Regards,
Mike VP8NO
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