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Topband: Inverted-L with coil on the top of the vertical section

To: <topband@contesting.com>
Subject: Topband: Inverted-L with coil on the top of the vertical section
From: "Adrian Fabry" <yo2naa@gmail.com>
Date: Wed, 11 Feb 2015 00:09:56 +0200
List-post: <topband@contesting.com">mailto:topband@contesting.com>
Hello all,

 

I'd like to build an Inverted-L antenna. Unfortunately the vertical section
will be only 8m (26 ft) high and the radial system not great (maybe 5 to 10
wires laying on the ground)

The simulation (with MMANA software) indicate 3.5 +j0 Ohm impedance. This is
very low so I think most of the power will be lost in the ground. 

In order to raise the impedance, I would insert a coil (about 75 uH) on the
top of the vertical section and restore the resonance with 48.7 pF series
capacitor on the feed point. 

This will raise the impedance to 34 ohm. 

 

Is this solution OK? Should I better place the coil at the feed point ?

 

I know it would be much better to increase the height of the vertical
section and to install more radials or a ground screen, but this is not
possible for the moment, so I have to find the best compromise.

 

 

Thanks for reading.

 

73 Ady YO2NAA

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