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LF: RE: Field Strength Measurements

To: "[email protected]" <[email protected]>
Subject: LF: RE: Field Strength Measurements
From: Rik Strobbe <[email protected]>
Date: Thu, 7 Apr 2016 22:24:25 +0000
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Thread-topic: Field Strength Measurements

Hello Chris,


(1) will give you the EMRP (Effective Monopole Radiated Power)

(2) will give you the EIRP (Effective Isotropic Radiated Power)

The formula P = 0.0203252(Ed)^2 will give you the ERP (Effective Radiated Power)


73, Rik  ON7YD - OR7T


Van: [email protected] [[email protected]] namens Chris Osborn [[email protected]]
Verzonden: donderdag 7 april 2016 23:58
Aan: LF Group
Onderwerp: LF: Field Strength Measurements


I've recently resurrected my old RF field strength meter as designed by PA0SE and published in the LF Experimenters' Handbook.
I've modifed it to measure signals in the MF band and have calibrated it with a home made Helmholtz coil arrangement.

This question may have been raised before but PA0SE gives the formula for deriving the transmitter power as

P = 0.0111 (Ed)^2  . . .   (1)

where E is the electrical field strength and d the distance

I've read in other places that the power from an isotropic radiator is

P = (Ed)^2 / 30

i.e.  0.0333 (Ed)^2  . . . . (2)

My calculated radiated power seems rather low so I'm wondering whether I should be using formula (2)

Any clarification would be most welcome.

Chris G3XIZ

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