Message-ID: <000c01c3466d$e8c96c40$2de086d4@erica>
From: "g3ldo" <g3ldo@ukonline.co.uk>
To: rsgb_lf_group@blacksheep.org
References: <000201c34648$df53b320$6c1686d4@captbrian>
Date: Wed, 9 Jul 2003 23:58:53 +0100
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Subject: LF: Re: Earth losses
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Bryan

>
> Is 24in wide 24 ft. long [inside the ridge of my roof } of aluminium foil
> tacked to the rafters not better as a top capacity than 100ft of top-wire
> down the garden ?.

Don't even think about it if you are considering transmitting. The voltages
at the top end of a loading coil at LF are very high, even at modest power
levels. Several of us have experienced fires or arcing with LF antennas for
one reason or another. A loft is a bad place to have a conflagration.
A loft or attic loading coil system feeding an external antenna can work
fine provided it is well engineered, see the I5TGC antenna system in the LF
Handbook.

> Either way I am stuck with 24' vertical  but my
> top-loading coil and feed point and capacity can be inside the attic.
>
> I thought that at LF,  losses through brickwork were so slight that it
> wouldn't matter that the vertical was almost touching brickwork at endwall
> of house

For dry brickwork that is probably true

> As a separate  matter does anyone know a site that gives figures for
> attenuation of sigs from an attic antenna at various frequencies ?? HF/VHF

At HF most lofts are fine. I did live in one old house where the slated roof
caused considerable attenuation but I don't know where these slates came
from. Modern tiles all seem OK.

Regards,
Peter, G3LDO