LF: Re: A question about loops for 136 and 500kHz TX

["Alan Melia" <alan.melia@btinternet.com>]

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
>