Re: LF: ERP<>EMRP

To:	[email protected]
Subject:	Re: LF: ERP<>EMRP
From:	Andy Talbot <[email protected]>
Date:	Fri, 22 Jan 2010 08:32:13 +0000
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Well, yes it is I suppose if you lump antenna directivity into the equation.

I^2.R is the actual power radiated.

Which direction it then goes is a different issue.

Anyway, what is the true directivity figure to use for a monopole ?

A very short dipole has 1.5 times directivity. Therefore a short monopole over perfect ground ought to have 3 times. Neither of which is 1.83

Andy
www.g4jnt.com

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2010/1/21 Stefan Schäfer <[email protected]>

Hi Andy,

Isn't it, the ERP is I^2*Rrad*1,83, if we assume a vertical antenna?

73, Stefan

________________________________

Von: [email protected] im Auftrag von Andy Talbot
Gesendet: Do 21.01.2010 20:27
An: [email protected]
Betreff: Re: LF: Re: M0BMU - any chance of some new ERP estimates please?

So go on: argue against the Rrad (an exact figure derived from basic electromag theory) and Rloss (easily measurable, called Ohms law) way of getting antenna efficiency.

Or ERP = I^2 . Rrad where I is measurable.

Only uncertainty in any of these techniques is the effective height of the antenna used to get Rrad, but absolute worst case, can only ever lead to 6dB error. The difference between no top hat and an infinite top hat

Andy
www.g4jnt.com <http://www.g4jnt.com/>

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