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From: "Graham" <g8fzk@g8fzk.fsnet.co.uk>
To: <rsgb_lf_group@blacksheep.org>
References: <AANLkTi=L7RmVBYd7=T36tyxvD1CeUi-3ZOSBeT7i2xmE@mail.gmail.com> <000d01cb3afb$9d1236d0$4001a8c0@lark>
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Date: Fri, 13 Aug 2010 17:27:07 +0100
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Subject: Re: LF: Re: A question about loops for 136 and 500kHz TX
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Alan,

Running  a delta  loop  at  GB4FPR , cheating a  bit as its  600  feet of 
wire , 90  feet  over salt  water  (when the  tide is in)  Andy's beacon 
shows  1/2 >  3/4 scale on the  S-meter , but I would  say the  long wire 
is a little  better , but  perhaps more  directional ,

G.

--------------------------------------------------
From: "Alan Melia" <alan.melia@btinternet.com>
Sent: Friday, August 13, 2010 4:24 PM
To: <rsgb_lf_group@blacksheep.org>
Subject: LF: Re: A question about loops for 136 and 500kHz TX

>
> Hi Roger if it is laid on the ground the currnet will couple to the lossy
> ground increasing the aerial loos and reducing the already low efficiency 
> of
> the loop. You might search for articles by Bill Ashlock who has done a lot
> of systematic experiments with TX loops in the States. I dont recall 
> anyone
> bar Dave Sargent using a loop in the UK.
>
> Alan G3NYK
>
>
>
> ----- Original Message ----- 
> From: "Roger Lapthorn" <rogerlapthorn@gmail.com>
> To: <rsgb_lf_group@blacksheep.org>
> Sent: Friday, August 13, 2010 4:08 PM
> Subject: LF: A question about loops for 136 and 500kHz TX
>
>
>> Having considered the antenna options for my small garden, I'm going to
>> erect a TX loop antenna rather than a Marconi vertical for 136kHz: the
>> earthing issues are removed and it is easier to build a capacitor
> selection
>> box (to tune and match the loop) than wind a huge loading coil and match
> it.
>> I've seen some of the webpages dealing with these and understand 
>> basically
>> what is needed (large loop area, thick wire, capacitor match-box, dealing
>> with high RF currents, etc). I understand the loop will have
> directionality
>> and nulls.
>>
>> My question is this. *Is there any reason why the bottom of the loop
> cannot
>> be laid along the ground rather than elevated a few metres?* Most designs
>> show the bottom elevated a bit, but if laid on the soil I could use thick
>> coax or multiple wires for part of the loop so reducing the loop
> resistance.
>>
>>
>> Views appreciated, although it may be a case of "suck it and see".
>>
>> 73s
>> Roger G3XBM
>>
>> -- 
>> http://g3xbm-qrp.blogspot.com/
>> http://www.g3xbm.co.uk
>> http://www.youtube.com/user/g3xbm
>> G3XBM   GQRP 1678    ISWL G11088
>>
>
>
>