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Message-ID: <000901c7b43e$64427f00$5e287ad5@w4o8m9>
From: "James Moritz" <james.moritz@btopenworld.com>
To: <rsgb_lf_group@blacksheep.org>
References: <004e01c7b36b$dc9f52d0$9d556a58@wgt01> <D523328AC9E40D4E8FE25E2E50D0C1690120C8@ORION.czd.org.uk>
Date: Thu, 21 Jun 2007 20:57:26 +0100
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Subject: LF: Re: Applying for a 500kHz NOV
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Dear Martyn, LF Group,

The approach I adopted goes something like:

-Calculate or measure capacitance and effective height / radiation
resistance of antenna (to do this, you also need the length of the top
section, and the spacing of the top wires in order to calculate capacitance
of vertical and top loading sections).

-Calculate antenna current required to get 0.1W ERP ( = sqrt (0.1W / [Rrad *
1.8]); this will be some hundreds of milliamps.

-From the antenna capacitance, work out the antenna reactance and multiply
by antenna current to get the antenna voltage.

-Make a "worst case" assumption that the field strength is (antenna
voltage)/(shortest distance to neighbors) - the actual field strength will
be less than this.

This will probably come out to some tens of volts/m, which Ofcom seem to
find acceptable.

Most people seem to be using CW at the moment; also, the very slow morse
QRSS and DFCW modes as used on 136kHz have seen some use.

Good luck with the application,

Cheers, Jim Moritz
73 de M0BMU

----- Original Message -----
From: "Martyn Kinder" <martyn@czd.org.uk>
To: <rsgb_lf_group@blacksheep.org>
Sent: Thursday, June 21, 2007 7:01 PM
Subject: LF: Applying for a 500kHz NOV


Hi all,

I am applying for a NOV for 500kHz.

I have a couple of questions which I am hoping you may be able to help
me with.

Assuming that I run QRO ERP (-10dBW) can someone give me some help to
what my field strength will be at the neighbours boundary.