[TowerTalk] Breakall short vertical

[Pete Smith <n4zr@contesting.com>]

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
The World HF Contest Station Database
was updated on June 5, 2004
2728 contest stations at
www.pvrc.org/WCSD/WCSDsearch.htm  

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