|To:||"[email protected]" <[email protected]>|
|Subject:||Re: LF: Re: RE: Field Strength Measurements|
|From:||Chris Osborn <[email protected]>|
|Date:||Fri, 8 Apr 2016 09:36:48 +0000 (UTC)|
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Many thanks for the rapid replies gentlemen; they are very much appreciated.
Rik, thanks for the explanation of the two formulae and I've inserted that ERP formula into my spreadsheet now - excellent !
Alan, I take measurements in open fields to the south of Biggleswade and at about 1 - 1.5 km distance from the transmitter.
Noted about the advantages of higher ground measurement but we're fairly flat around here - HI !
I'll look at the O/S map and see what I can do.
Transmitting 56 watts my ERP was calculated as being 0.38 watts which just seemed rather low.
My aerial is a 40 m long inverted 'L' at 9m mean height with a reasonable ground system.
Making measurments of G4GIR's transmissions with his 260 watts at 16 km returned a value of 0.88 watts ERP
On Friday, 8 April 2016, 0:24, Alan Melia <[email protected]> wrote:
Chris two other points
1. How far from the aerial are you taking the measurement .....you need to be at least 300 to 500 metres away
2 Because of ground loss problems even the best (fully in the clear) amateur short aerials measure around 5 to 6 dB low.(that is a 136kHz observation.) Often a better reading is taken say a mile away on slightly elevated ground to the aerial site. Jim Moritz did tests in a field adjacent to the Puckeridge Decca mast, with a 10m high inverted L.
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