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Re: Topband: WB4ENE - MRA (minimal reactance antenna)

To: Ken@Crawley.org, Topband <topband@contesting.com>
Subject: Re: Topband: WB4ENE - MRA (minimal reactance antenna)
From: David Gilbert <rimradio@direcway.com>
Date: Sat, 19 Nov 2005 16:11:42 -0700
List-post: <mailto:topband@contesting.com>

Hi, Ken.

Just to clarify ... I didn't say that the antenna needed a good ground 
to work.  I said that it's radiating efficiency was dependent upon 
whether the ground was lossy or not, the same as any vertically 
polarized antenna close to ground.  I was going by the picture I saw on 
your website that showed it resting on or near ground.

If the antenna were positioned far from ground, such as on top of a tall 
building, the MRA would function more like an elevated ground plane 
antenna and radiation efficiency would be less a function of ground 
conditions.  That would be a pretty tall building at AM broadcast 
wavelengths, though.

I remain impressed by the ambitious effort you put into reducing the 
conductive losses of the MRA, but it just seems to me that for most 
installations the same or better performance could be gotten at much 
lower cost via more conventional means of loading.  It would be 
interesting to compare far-field measurements of the MRA with, say, a 25 
foot top-loaded vertical with a heavy ground mesh under it.

Best of luck with your upcoming tests.

Take care es 73,
Dave   AB7E


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