Date: Wed, 15 Dec 2010 10:24:05 +0100 (CET)
From: =?UTF-8?Q?"Horst_St=C3=B6cker"?= <horst.stoecker@web.de>
To: rsgb_lf_group@blacksheep.org
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Subject: Re: LF: Re: Earth Antennnas - General question
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Hello Mal,
I am not a great technician but even to me it seems clear, that it's an ob=
solete discussion. I do not think that on this low frequencies (vlf) it ma=
kes a remarcable difference if the wire is directly on the ground or not.=
 Maybe in theory but not in practice as you find grass, little bushes, roc=
ks outside. Also you can not assume equal ground conductivity underneath=
 the antenna over the whole distance. Regarding the wave length I assume=
 even 6m should not make a great difference.
In summer I did some local tests on 9kHz at Erpeler Ley near Bonn. No sens=
ations to talk about, but I have learned a few things about VLF antennas.
I took about 100m of wire, my dds, pa and the line transformer. First I to=
ok the antenna as a Marconi (10m high, 90m top load). After that I connect=
ed the other end with some ground rods. Then I took down the antenna so it=
 was directly on the ground. And after that I used it as a kite antenna.
Now you can bet on what had the best results regarding the near field with=
 walk around reception by ear. Of course it was the kite antenna. The grou=
nd antenna did work rqually good or bad with no difference if lying direct=
ly on the ground or elevated a few meters. Mounted Marconi style (10h 90t)=
 was worst.
(Even on 500kHz there must be a point where ratio of height and top load=
 of a Marconi antenna gives the maximum result. The 10h 90t did work worse=
 than my 10h 20t. I assume that the top load was coupling more hf to the=
 ground than the higher antenna capacity could result in radiation.)
Horst DO1KHS/DI2AN

=C2=A0-----Urspr=C3=BCngliche Nachricht-----
Von: "mal hamilton" <g3kevmal@talktalk.net>
Gesendet: 15.12.2010 00:47:29
An: rsgb_lf_group@blacksheep.org
Betreff: LF: Re: Earth Antennnas - General question

>Gerhard
>Yes the antennas described by Stefan and Roger and others are of the LOSS=
Y
>variety and similar to Beverages.
>I have made this observation before. I cannot see how these elevated
>antennas can be considered Earth Mode since they propagate a signal into=
 the
>ether to be received at a distance by another elevated antenna several
>metres above ground.
>de mal/g3kev
>
>
>----- Original Message -----
>From: "Gerhard Hickl" <gerhard.hickl@aon.at>
>To: <rsgb_lf_group@blacksheep.org>
>Sent: Tuesday, December 14, 2010 9:06 PM
>Subject: LF: Earth Antennnas - General question
>
>
>> Hi all !
>>
>> I was following the whole discussion about the so called "earth-mode"
>> and the used antennas with interest.
>>
>> Mal told us that he sees those antennas as "lossy dipoles" while others
>> stated they are "true" earth-antennas.
>>
>> I don't have the theoretical background to tell you why but out of my
>> feeling, all those antennas described remind me on the well-known
>> Beverage-Antenna system.
>>
>> Two wires of any layout, diameter, height and length terminated by a
>> "resistor"...the soil.
>>
>> Could that be a way we could look at this kind of antenna?
>> And if so, what would it explain?
>>
>> 73
>> OE3GHB
>> Gerhard
>>
>>
>>
>>
>>
>>
>>
>
>
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