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To: topband@contesting.com
From: John Brosnahan <broz@csn.net>
Subject: Re: TopBand: Folded unipoles
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An impedance transformer transforms whatever impedance it sees.
Doesn't matter if it is a transmission line transformer, a toroidal
transformer, or a transformer made by folding the monopole into
"half of a folded-dipole".

The impedance that gets transformed includes the ground loss
component.  So the percentage of power lost in ground losses
remains the same when folding the monopole compared to
a normal folded monopole.  You don't get something for nothing.

But there may be other reasons to fold the monopole.  It allows 
for grounding of one side of the monopole--very useful for lightning
protection.  It can broadband the a monopole somewhat by "fattening"
it.  And it can raise the impedance of the antenna system (including
ground losses) to a higher value that may allow different options
for matching circuitry.

But it won't help the efficiency.
John  W0UN


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