Message-ID: <5B8F9291.7090601@posteo.de>
Date: Wed, 05 Sep 2018 10:23:45 +0200
From: DK7FC <selberdenken@posteo.de>
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To: rsgb_lf_group@blacksheep.org
References: <165a8bb827e.marcocadeddu@tin.it>
In-Reply-To: <165a8bb827e.marcocadeddu@tin.it>
Subject: Re: R: LF: Antenna environment changes
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Paul,

did the LF loss resistance drop after mowing the grass?
Someone should try to roll out household aluminium foil completely 
within a radius of the height of the antenna to see how it loweres the 
losses :-) Not so expensive actually.

73, Stefan

Am 05.09.2018 09:56, schrieb marcocadeddu@tin.it:
> .. a wingbeat of a butterfly..
>
> be careful to move around the antenna and touch metal parts while 
> transmitting Paul it is a very "reactive" area not only for the field 
> strenght concept :-))
> I guess that the pipe laying on the ground it is part of the ground 
> itself (maybe improving it ) when you rise it from ground level and 
> eventually connect to other existing metal parts you really make 
> change in the environment of the antenna (it is like to tophat wires 
> moving in the space when wind blows)
>
> 73, Marco IK1HSS
>
> ----Messaggio originale----
> Da: paul@n1bug.com
> Data: 5-set-2018 1.09
> A: "rsgb_lf_group@blacksheep.org"<rsgb_lf_group@blacksheep.org>, 
> "rsgb_lf_group@yahoogroups.co.uk"<rsgb_lf_group@yahoogroups.co.uk>, 
> "Discussion of the Lowfer (US, European, & UK) and MedFer 
> bands"<lowfer@mailman.qth.net>
> Ogg: LF: Antenna environment changes
>
> Subtitle: Be careful what you do in the vicinity of your LF antennas...
>
> I had a 14m length of aluminum tube (proposed 30 meter rotatable
> dipole) laying on the ground just under one end of the top hat of
> the LF antenna. Today I picked it up and moved it about 20 meters
> away. To get it off the ground for mowing, I ran it through the
> lattice of a short tower (9m) that is not at all under the LF top
> hat. I placed it about 2m above ground. This caused the LF antenna
> resonance to change so much I could not retune with the variometer!
> It was quite a large shift in resonant frequency.
>
> I then experimented with moving the piece of aluminum tube around.
> It seems I can lay it on the ground anywhere I want with no affect
> to the LF antenna. But put it one or two meters above ground
> connected to another tower or mast and the LF antenna is drastically
> changed.
>
> I must remember not to move any pieces of metal around while the
> beacon is active! :-)
>
> Paul
>
>
>