Message-ID: <5B8FCCD1.4080604@posteo.de>
Date: Wed, 05 Sep 2018 14:32:17 +0200
From: DK7FC <selberdenken@posteo.de>
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To: rsgb_lf_group@blacksheep.org
References: <165a8bb827e.marcocadeddu@tin.it> <5B8F9291.7090601@posteo.de>,<2f2c5632-b82a-91c7-3502-d88b7657d038@n1bug.com> <1536142926551.20983@kuleuven.be>
In-Reply-To: <1536142926551.20983@kuleuven.be>
Subject: Re: R: LF: Antenna environment changes
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Hi Rik,

At some point it is simply easier to rise the POWER. Same here at the 
moment on the new antenna :-)

73, Stefan

Am 05.09.2018 12:22, schrieb Rik Strobbe:
> Hi Paul,
>
> same here, losses are high in summer: up to 70 Ohm (475 kHz) or 180 Ohm (137 kHz). In winter it drops to 35 Ohm (475 kHz) and 120 Ohm (137kHz).
> I always assumed it was not so much affected the soil but rather by all the trees surrounding the antenna that loose their leaves and go to "sleep" in winter.
> Last february I raised the antenna from 12m to 14m in my attempt to get some extra ERP to cross the Atlantic and actually the losses increased slightly. I thought this was caused by the topload coming closer to some branches. But fortunately the overall effect was positive and we had our QSO ;-)
>
> 73, Rik  ON7YD - OR7T
>
> ________________________________________
> Van: owner-rsgb_lf_group@blacksheep.org<owner-rsgb_lf_group@blacksheep.org>  namens N1BUG<paul@n1bug.com>
> Verzonden: woensdag 5 september 2018 11:06
> Aan: rsgb_lf_group@blacksheep.org
> Onderwerp: Re: R: LF: Antenna environment changes
>
> Marco,
>
> ... a wingbeat of a butterfly... is very descriptive. I like it. :)
> Maybe with a sensitive detector I can use the LF antenna to count
> birds flying under it. :)
>
> Stefan,
>
> I have not seen any significant change in loss resistance during the
> summer. Rain, dry... hot, less hot... grass mowed or not mowed seem
> to have not much influence. My loss resistance in summer is very
> high. I need that aluminum foil!
>
> During the winter my loss resistance changed a lot with temperature.
> Colder = lower resistance. I did not understand what was changing. I
> do not think variations in temperature could affect the ground very
> much with 1m of snow over it but maybe I am wrong. Perhaps it was
> the snow itself changing with temperature, or maybe it was the
> nearby trees.
>
> 73,
> Paul
>
>
> On 09/05/2018 04:23 AM, DK7FC wrote:
>    
>> 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
>>>        
>
>