Message-ID: <4B8CE53D.4050300@ukonline.co.uk>
Date: Tue, 02 Mar 2010 10:15:25 +0000
From: Peter Dodd <g3ldo@ukonline.co.uk>
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Subject: Re: LF: 9kHz without high voltage
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When I was technical editor at the RSGB in 1994 an interesting article 
was received from Prof Jennison G2AJV on a toroidal antenna. Before 
publishing it I felt that I should make one. This turned out to be a 
problem but after several phone calls with G2AJV a 14MHz version using 
two toroid coils and no end plates was made to work
  The article was published in RadCom April/May 1994 'The G2AJV Toroidal 
Antenna'.

After the article was published I continued to experiment with this 
antenna. I also met Prof James Corum, K1AON at Dayton, who passed on 
additional information on this antenna - he has a patent on the toroid 
antenna.

Eventually my 14MHz version performed as well as a 14MHz  loaded whip 
antenna and the whole saga was written up in RadCom August 1994 
'Evaluation of the G2AJV toroid antenna'.

All these RadCom articles are well illustrated with colour photos.

Regards

Peter, G3LDO




On 01/03/2010 19:56, Graham wrote:
> Making  a   Torodial  antenna, as  presented at the  Egham HFC  would 
> be a good  start .. the  concept  of the  mirror differed  from the  
> published articles ... I made one and oddly it  worked  quite  well  
> at  Hf  ..how it worked ive no idea .how a  12 inch diameter  coil 
> resting on a old  no-entry sign (alloy plate) one end fed with coax 
> from the  atu the  other  open achived qso's  from 160  to  10 mtrs .. 
> who  knows .... .its  still hanging in the  shed .. but a  large one 
> may work at  9 khz without the  need  for all  the  coils  etc ...  
> Did  anyone else  attend the  lecture ?.. it followed the  chap from 
> Birmingham with a selection  of  loop  antennas . ....
>
> G ...
>
> NB .. Can anyone  read this  .. as  '' design of toroidal reflector 
> ..... Antennas ''  is  showing in the  google  search
>
> http://www.informaworld.com/smpp/content~content=a770413350&db=all
>
> --------------------------------------------------
> From: "Alexander S. Yurkov" <fitec@omskcity.com>
> Sent: Monday, March 01, 2010 1:59 AM
> To: <rsgb_lf_group@blacksheep.org>
> Subject: LF: 9kHz without high voltage
>
>>
>>
>> I was wonder if it is posible to use a loop on 9 kHz. Serious problem
>> to radiate 9 kHz is high voltage we saw. Loop has that advantage that
>> voltage is not too high. Then i do some estimations. Let's assume 
>> vertical
>> loop 15m x 50 m with 20 mm diameter coper tube as a wire. Then 
>> effectivity
>> of such a loop on 9 kHz is about -65 dB. It is adequate to radiate 1 mW
>> on 9kHz (I=250A, TX power about 4 kW). We saw such a radiation should
>> give abt 100 km  distance in QRSS. Besides such a loop is wellsuited
>> for 136 kHz. On 136 kHz it effectivity should be about -25 dB. Not too
>> bad: 1 W radiation with 400 W TX :-)
>>
>> Regards,
>> Alexander
>>
>>
>>
>>
>
>
>
>
>