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Re: [CQ-Contest] How to start a run

To: cq-contest@contesting.com
Subject: Re: [CQ-Contest] How to start a run
From: Charlie Ocker via CQ-Contest <cq-contest@contesting.com>
Reply-to: Charlie Ocker <N9CO@aol.com>
Date: Sun, 21 Aug 2016 20:35:57 -0500
List-post: <cq-contest@contesting.com">mailto:cq-contest@contesting.com>
A quick analysis with EZNEC v6.0+ reveals that a 125' dipole @ 14.175 MHz yields a nice cloverleaf pattern with peaks of 3.67 dBi. If the dipole is oriented N/S, the peaks are at 37, 142, 218, and 323 degrees. There are some deep nulls, too: -21.95 dBi E/W, and -99.99 dBi N/S.

The feedpoint impedance is 1048 + J 1421 ohms, so you'll definitely need open wire line to feed this antenna.

Now, over "real" ground in EZNEC (using midwest USA soil), with the antenna being flat @ 40' above the modeled ground, the pattern peaks are 8.99 dBi @ 40, 140, 220, and 320 degrees. The lobes are fatter than in free space: beamwidth is 34.5 degrees, with the -3dB bearings of 24.9 and 59.4 for the 40 degree lobe.

The E/W nulls are even deeper, but the N/S ones are only down -2.35 dBi from the peak lobes.

The elevation plot is sorta funky looking with the peak being 2.37 dBi @ 38 degrees. This antenna looks like it would well in a domestic contest.

The feedpoint impedance looks better: 922.3 + J 1388 ohms. Again, you'd want to use open wire line.

On a practical note, I used a 140' dipole fed with that brown close spaced "ladder line" stuff to a homebrew balanced L-network tuner when I was working in Colorado from 2002 to 2004. The dipole was maybe 40' at one end, but it was over uneven ground and the other end was 25 or 30' high. 100w was all I ever used - NAQP's were a favorite, along with SS and state qso parties. I never felt handicapped with this antenna on 20m for domestic contests.

73 es GL!

Charlie  N9CO


On 8/21/2016 4:41 PM, Steve London wrote:
You should be looking at the K1AR CQWW CW contest results over the past
10+ years.

I believe that John has nothing more than a center-fed dipole, fed with
open-wire, and using a real Johnson antenna tuner. His is up
considerably higher - 80' or so ? No towers, no wire beams.

73,
Steve, N2IC

On 08/21/2016 02:29 PM, john@kk9a.com wrote:
How could this be made into an excellent 20m antenna? It will have
very deep
nulls (30dB+) and super high SWR, plus likely high feedline loss.  A 32'
dipole would be a better antenna.

John KK9A

To:    Timothy Holmes <taholmes160@gmail.com>, cq-contest@contesting.com
Subject:    Re: [CQ-Contest] How to start a run
From:    Steve London <n2icarrl@gmail.com>
Reply-to:    n2ic@arrl.net
Date:    Sun, 21 Aug 2016 10:24:31 -0600

On 08/21/2016 10:11 AM, Timothy Holmes wrote:
Hi steve
To answer your questions
My antenna was a 125 ft dipole up 40 ft


Fed and tuned how ? How high are the ends ?
Done right, this can be an excellent antenna. Done wrong, this makes a
poor
dummy load.

73,
Steve, N2IC

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