R: Topband: Inverted L

Maurizio Panicara i4jmy@iol.it
Mon, 24 Jan 2000 16:10:38 +0100


HA0DU wrote:

>I only put up a 23 m
> vertical with a 17 m wire connected at the top. That would be an inverted
> "L", right? As of now, the antenna is fed directly with a 50 ohm coax, SWR
> is about 1.2:1, not bad.

 The impedance of a 23m top loaded vertical shouldn't match 1.2:1 to 50 ohm
unless somewere losses are present and add to the impedance at resonance
that should range in the 20-25 ohm area..
90% the way to fix the problem is checking connections or improving the
ground plane.
When losses will be reasonably reduced then you measure about 2:1 SWR in a
direct feed.
An unnun transformer or a quarter wave line will be the a possible and
convenient match to 50 Ohm.

73,
Mauri I4JMY



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