Message-Id: <5.1.0.14.0.20040716141651.0197d248@u0019445.kuleuven.be>
Date: Fri, 16 Jul 2004 14:31:53 +0200
To: rsgb_lf_group@blacksheep.org
From: Rik Strobbe <rik.strobbe@fys.kuleuven.ac.be>
In-Reply-To: <40F7C3CC.3060002@cytanet.com.cy>
Mime-Version: 1.0
Subject: Re: LF: Feeding grounded tower on 136KHz
Content-Type: text/plain; charset=us-ascii; format=flowed
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org
Content-transfer-encoding: 8bit

Hello Geoff,

a pity you cannot climb the tower or in any other way get a couple of wire 
up to the top.
Shunt feeding will be very difficult as you will face a impedance of only a 
few micro-Ohms. So you can expect huge currents (= need of thick wire) and 
high losses in the matching circuitry.
60m might seem a lot, but it's only 2.7% of the wavelength. So scaled to 
160m it's no more than a 4.5m tower or scaled to 20m just a 60cm tower.

73, Rik ON7YD

At 15:02 16/07/2004 +0300, you wrote:
>Hello,
>
>New to 136KHz.
>
>Callsigns: ZC4CW or ZC4LOW (for experiments).
>
>I need advice on using a grounded tower as a vertical radiator on 136KHz.
>It's approximately 60m high and I can't climb it. This rules out some
>of the existing methods which rely on accessing the top of the tower.
>Shunt feeding has proven effective on 160m, however can this be done
>on 136KHz.  I would be open to other alternatives.
>
>Thankyou,
>
>Geoff
>
>
>
>
>