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[TowerTalk] Breakall short vertical

Subject: [TowerTalk] Breakall short vertical
From: Pete Smith <>
Date: Fri, 11 Jun 2004 07:49:26 -0400
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I have been doing some modeling on Jim Breakall's shortened vertical for 160 meters. The antenna actually involves 4 45-foot verticals, spaced quite close together, with horizontal flattops making up the rest of the resonant length for the antennas -- rather like low inverted Ls. The verticals have a feedpoint impedance of about 12 ohms each, so he parallels them a short distance from the base, yielding a convenient 50-ohm feedpoint impedance. It shows a feedpoint impedance of almost exactly 50 ohms. Modeled gain is approximately the dsame as -- a little higher than -- a vertical monopole. 2:1 SWR bandwidth is over 100 KHZ, so for a person with trees conveniently situated, this could be tempting.

Am I right to assume that although the feedpoint impedance is 50 ohms, the ground loss picture is really closer to that of a single short inverted L, and is established by the feedpoint impedance of a single L rather than the 4 together? Any other comments on the antenna?

73, Pete N4ZR
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