From: "jannsen" <0482183881-0001@t-online.de>
To: rsgb_lf_group@blacksheep.org
References: <5.1.0.14.0.20020720155223.00ae8e80@gemini.herts.ac.uk>
Subject: Re: LF: Calculating ERP from measured field strength
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Date: Sat, 20 Jul 2002 18:24:18 +0200
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James Moritz schrieb:
> Dear LF Group,
>
> I'm pleased to see PA0SE's FS measurements agree well with my own - it 
> looks like we are getting quite good at this now!. I measured my ERP a 
> couple of weeks ago, after making some slight improvements to my antenna; 
> it is still an inverted L, but it now has an average height of around 9.5m, 
> and the same 40m length as before. The 400mW figure was derived from an 
> average of 11 field strength measurements at distances between about 1.5 
> and 3km. Comparing these to measurements I did last year at the same 
> locations, it is interesting to see that the variations in calculated ERP 
> between different locations are very consistent - ie. if one location gave 
> a measurement 1dB above the average last year, it was also 1dB above the 
> average this year, so whatever causes the variation is stable over quite 
> long periods of time. All the ERPs  were within about 1.5dB of the average
>  ERP.
>
> The antenna current of 4.6A is well down on what I get on a cold winter's 
> day, so I think this antenna should give 500-600mW ERP under good conditions
>
> I used a "Jason" mode test signal when performing the measurements - this 
> is ideal for FS measurement, because it is practically a continuous 
> carrier, and makes it easy to measure the amplitude.
>
> Cheers, Jim Moritz
> 73 de M0BMU
>
>
Hi Jim,

you measured field strength at distances between about 1.5 and 3km.
did you ever measure at distances >3xlambda, p.e. abt 7km?
if you did, did you notice different results caculating the ERP?

regards
Uwe/dj8wx