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Topband: Propagation and evaluation of antennas...

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Subject: Topband: Propagation and evaluation of antennas...
From: "Lars Harlin" <lars.harlin@one.se>
Date: Tue, 13 Jan 2009 05:30:07 +0100
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Hi all!
Not much on the band this morning so better be on the keyboard...
Regarding propagation on this band its an interesting issue. Have found many 
times that even if the A- and K-index is at low values, like this morning, 
still there is no propagation. My experience, living at 63 deg north,is that 
the solar wind data is a far better indicator. This morning both the A- and 
K-index = 0, but with high solar wind velocity and density levels. And the band 
is quiet. Have also seen the opposite many times this season, So without 
knowing exactly how they relate, thats my reflection. 

Agree that its hard to compare different antennas if you dont have a reference 
antenna to compare to. Its then more like a gut feeling that one can get after 
beeing on the band for a while, in different propagation, different times and 
how well one compete in pile ups. Myself I've been testing a new antenna idea 
here for a couple of weeks, unfortunally without a reference antenna but by 
now, with a good gut feeling. This antenna needs no radials, yet it has about 
the same vertical far field diagram as a quarter wave vertical antenna. You can 
easiest describe the antenna as a half square that has been stretched out into 
an inv vee configuration with its apex at 17 meters. Total length is 158 m and 
the feedpoint is 25% (abt 40m ) from one of the ends. It has a comfortable 
feedpoint impedance for direct coax feed. Have a model in Eznec of the antenna 
if anyone out there is interested. Will do more evaluating, but so far the 
results are very satisfying.

73 de Lars, SM3BDZ
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