[UK-CONTEST] 80m antennas

[g3ory at lineone.net]

Hi Guys,

Ray G3HRH published an article in the RSGB Bulletin years and years 
ago and included a ground conductivity map of the UK. However, it was a 
pretty small scale affair and was never going to differentiate over a 
few 100s of yards.

Measurements are not very easy but comparisons are.  If you use an 80m 
ARDF receiver with the E field sense antenna in circuit with the loop, 
rotate it so that the 'back lobe' is pointing at a vertically polarised 
test TX. Then raise and lower the receiver. The height of minimum 
signal is an indication of ground conductivity. The lower the better.
The highest I have observed was shoulder height in some German forest 
where I was once competing. Lutterworth recreation ground is about 
waist height and therefore significantly better.  The results are only 
applicable to the one receiver since it is likely to have a unique 
combination of loop size, E-field antenna size and active antenna gain.

73 Bob

>----Original Message----
>From: dave at davesergeant.com
>Date: 22/04/2010 19:39 
>To: "UK Contesting"<uk-contest at contesting.com>
>Subj: Re: [UK-CONTEST] 80m antennas
>
>On 22 Apr 2010 at 18:49, Roger G3SXW wrote:
>
>> Callum - there's no such thing as 'average-uk'. Ground varies from 
clay
>> to sand to granite to . . . . within small distances.Geological 
maps
>> helped me decide which house to buy when I saw that one is on the 
London
>> Clay Belt (Thames) and the other wasn't. 73 de Roger/G3SXW.
>
>Can the geological maps tell you this to fine enough accuracy for 
this? 
>My house is built on sand - fortunately with good foundations - and 
Top 
>Band is effectively a right off. But Richard G4ZFE only a few 
hundred 
>yards away is on clay, as is Tony G3OFW at a similar distance. So 
there 
>seems no easy rule.
>
>73 Dave G3YMC
>
>http://www.davesergeant.com
>
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