Re: LF: ERP<>EMRP

[Andy Talbot <andy.g4jnt@googlemail.com>]

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 <schaefer@hst.tu-darmstadt.de>

Hi Andy,

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

73, Stefan

________________________________

Von: owner-rsgb_lf_group@blacksheep.org im Auftrag von Andy Talbot
Gesendet: Do 21.01.2010 20:27
An: rsgb_lf_group@blacksheep.org
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/>