From: <hvanesce@comcast.net>
To: <rsgb_lf_group@blacksheep.org>
References: <165a8bb827e.marcocadeddu@tin.it> <5B8F9291.7090601@posteo.de> <2f2c5632-b82a-91c7-3502-d88b7657d038@n1bug.com>
In-Reply-To: <2f2c5632-b82a-91c7-3502-d88b7657d038@n1bug.com>
Date: Wed, 5 Sep 2018 11:26:23 -0400
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Subject: RE: R: LF: Antenna environment changes
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Paul,

Probably need binoculars for birds, but with your extra detector you could see your car and garage doors open/close, and catch anyone moving your aluminum tube, as long as any of these objects is less than (roughly) 3 object-lengths from the sensor or the TX antenna. Great fun on poor-propagation days.

73,

Jim AA5BW
 

-----Original Message-----
From: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of N1BUG
Sent: Wednesday, September 5, 2018 5:07 AM
To: rsgb_lf_group@blacksheep.org
Subject: 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