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Re: [Antennaware] Terminated Vertical

To: "Terry Conboy" <>, <>,"K9AY" <>
Subject: Re: [Antennaware] Terminated Vertical
From: "Andy Ikin" <>
Reply-to: Andy Ikin <>
Date: Thu, 27 Dec 2007 23:07:57 -0000
List-post: <>
Good evening Guys,

I would like to thank both Terry and Gary for their off-line and on-line 
response to my question posted below.

> Good morning Guys,
> It is possible to achieve the same reception pattern of a ground mounted
> vertical using a 22ft aluminium pole with 2 sloping wires affixed to the
> top of the pole? Each wire comes out say 15ft from the pole ( 5ft above
> ground ), then bends back towards the base of the  pole and is connected
> to a ground rod via a 1k resistor i.e. the antenna looks like a single
> K9AY loop with 2 termination resistors. The insulated 22ft aluminium pole
> and the ground would be connected to a high Z input bipolar buffer
> amplifier with common mode feeder isolation choke.
> This configuration ( if it works) would provide lower noise than a FET
> active vertical with higher immunity to static damage! Also the amplifier
> would see a resistance loaded antenna rather than a small capactance of a
> whip antenna.
> 73
> Andy  G8LUG

Terry was very kind enough to model the above idea and with  a 500 Ohm shunt 
on the amplifier input. Both models provided  a typical vertical Elv. and 
Azi. pattern. However, dual termination provides a much lower capacitve 
reactance compared to the 500 Ohm shunt from 0.5 to 2MHz. Thus I believe, 
the dual termination will be ideal for driving a tranformerless unity gain 
bipolar buffer amplifier. This hopefully should provide some additional gain 
and with a well defined phase charateristic for use in wideband endfire 



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