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[TowerTalk] End feeding a half-wave vetical

To: "towertalk@contesting.com" <towertalk@contesting.com>
Subject: [TowerTalk] End feeding a half-wave vetical
From: Jim Smith <jimsmith@shaw.ca>
Date: Wed, 01 Jun 2005 00:24:59 -0700
List-post: <mailto:towertalk@contesting.com>
I want to end-feed a half wave vertical so I can get a nice low angle of 
radiation.  The base of the antenna would be about 0.05 to 0.10 
wavelengths above ground.  It looks like the antenna impedance will be 
around 4,000 ohms.  I would prefer not to use tuned circuits or stubs as 
I would like the device to work over a 2:1 frequency range.  (No, I'm 
not expecting the antenna to be a half wave over a 2:1 frequency range!! 
I would have 2 different antennas to choose from.)  Power level is 200W.

I was thinking that an auto-transformer with a 9:1 turns ratio would do 
the job and provide a reasonably low SWR for 50 ohm coax.  I figure on 
making the primary winding reactance about 500 Ohms at the lowest 
frequency of interest and adding 8 times as many turns for the 
secondary, presumably all on a suitable toroid.  The wire insulation 
would have to be suitable to withstand several hundred volts.

The auto-transformer would also nicely solve the static drain problem.

Am I nuts or is this actually feasible?

If it isn't, my next step would be to look into stubs.

73 de Jim Smith   VE7FO

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