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Date: Sat, 19 Dec 2009 13:48:35 +0000
Message-ID: <fc7eccec0912190548o1bf2851bjcf60e442670649af@mail.gmail.com>
From: Andy Talbot <andy.g4jnt@googlemail.com>
To: rsgb_lf_group@blacksheep.org
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Subject: Re: LF: Re: Noise cancelling by using optic transmission of RX 
	signals
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In which case, mounting it on top of a 20m high steel framed building
is like having a 20m whip????

Or does the size of the plane under the active element matter.   Our
works one has an antenna platform of a few metres square of metal grid
which itself is a few metres above the roof of the actual building
(erected to keep antennas above air conditioning plant and safety
walls)

Andy
www.g4jnt.com

This email has been scanned for damaging side-effects by the health
and safety police



2009/12/19  <jrusgrove@comcast.net>:
>> I think the role of the ground with active whips is often neglected -=
 the
>> output of the whip preamp is the voltage differential between the whip
>> element and the circuit ground, so the ground connection is just as muc=
h
>> part of the antenna as the whip element itself is.
>
> That's an important point that is often overlooked or ignored. A mini wh=
ip
> mounted up at 5 meters is a 5 meter antenna. You can easily prove this=
 by
> mounting it at ground zero on top of a ground screen. Been there, done=
 that.
>
> Jay W1VD =A0WD2XNS =A0WE2XGR
>
>