Message-ID: <D1436F37FA844F319A50FD405C728BCE@AGB>
From: "Graham" <g8fzk@g8fzk.fsnet.co.uk>
To: <rsgb_lf_group@blacksheep.org>
References: <001301d0f2ae$fa2eb260$6401a8c0@ehnebrcdvojcgn> <21D465C632E748AEB1B44B29D0A538CA@gnat>
In-Reply-To: <21D465C632E748AEB1B44B29D0A538CA@gnat>
Date: Sat, 19 Sep 2015 12:26:36 +0100
MIME-Version: 1.0
Importance: Normal
Subject: Re: LF: Re: Ground
Content-Type: text/plain;
	format=flowed;
	charset="iso-8859-2";
	reply-type=response
Content-Transfer-Encoding: 7bit
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org
Status: O

In saying that ,   I have the  idea  capacity to  ground, may be  more 
important than  'resonant' length , besides ,  in the  ground , the 
effective length must be  longer , as the  Vfactor of the  ground , is not 
the  same as  free  space ?

There  are some , huge signals rolling  Down under , where the  stations 
are located  in the  outback, 100's of miles from water , with  nothing  but 
'dry land'  A circular  perimeter fence some  miles long seems to  do  the 
trick

Bob  over in NY State  , uses  wire  mesh to  cover  his  front  lawn  , 
granted bigger than the  average , but  again , capacity as opposed to 
resonance ?

May be , just  make a  large  ground  'mat' and  tune against  that ?   loop 
couple  the  ATU  as the  tuner earth and the  equipment will  not be  the 
same

Or -If there is the height , use a  Loop  ?

73-Graham
G0NBD


NB  -   Steel tape  ?

--------------------------------------------------
From: "Alan Melia" <alan.melia@btinternet.com>
Sent: Saturday, September 19, 2015 11:24 AM
To: <rsgb_lf_group@blacksheep.org>
Subject: LF: Re: Ground

> Sadly Marcin there is probably no answer to your question. Over the early 
> years of LF activity I tried to make sense of the various "recipes" that 
> were floating around. I found that in general they don't necessarily work 
> for you. The reason being that the local ground condition varies widely at 
> different locations and in various weather patterns. The commercial site 
> designs bear little relation to amateur dimensions.
>
> Eventually I came to the conclusion that the only way to proceed was to do 
> measurements at your site and see what strategy is the best. The "best" 
> solution will depend very much on the type of antenna you intend to erect 
> above it. The idea that quantities radials are necessary by comparision 
> with 160m and commercial systems is a myth. To be reasonably effective 
> radials need to me of the order of 1/8th wavelength long at least. This is 
> way beyond practical amateur site dimensions. Running one conductor along 
> the ground under a top-wire (of say an inv L) has a positive effect, but 
> often running out more can be a waste of effort and money. Again it depens 
> on your local conditions. These measurements proved that after you reach 
> the diminishing returns point of ground stakes and counterpoises, then 
> increasing the antenna capacity has most effect. It seems 
> counter-intuitive but putting more horizonal wire in the air reduces the 
> "ground loss" !! In my case doubling the capacity halved the "ground 
> loss".
>
> At LF in amateur situations the loss resistance is very often not due to 
> grounding but to the effect of the surrounding environment. Commercial 
> station chose open land and do not try to install antenna in the middle of 
> a forest. Amateurs have to deal with building and foliage with the near 
> field range of the radiator. There is no advice in the manuals about this 
> and the condition is not modelled well (or at all !) in simulator 
> packages.
>
> Alan
> G3NYK
>
>
> ----- Original Message ----- 
> From: "Marcin" <bxi@go2.pl>
> To: <rsgb_lf_group@blacksheep.org>
> Sent: Saturday, September 19, 2015 8:44 AM
> Subject: LF: Ground
>
>
>> Hello,
>>
>> I'd like to design a ground for 136kHz/472kHz. I have a few hundred 
>> metres
>> of steel tape at my disposal for this. I'd like to find out how deep into
>> ground 136kHz and 472kHz respectively can go?
>> How deep do I have to dig the tape for 136kHz and for 472kHz, or what 
>> would
>> suit both frequencies?
>>
>> Thanks in advance.
>> 73! Marcin SQ2BXI
>>
>>
>
>