[Lf] [Fwd: LF: IK2DED beacon and E field probe.]

[Andre Kesteloot]

Rik Strobbe wrote:

> >ERP is mainly determed by antenna current and efffective height. If this
> >is known then it is very simple to estimate radiated power. Certanly this
> >is very aproximative estimation. But something is better then nothing :-)
>
> Hi Alex,
>
> be careful with that. I speak from my own experience :
> Antenna = 14m heigh inverted-L with elevated loading coil and 4 x 23m
> topload wire, calculated and simulated Rrad = +/- 0.06 Ohm
> Antenna current = 1.8A
> Theory : radiated power = 0.06*1.8^2 = 194mW EMRP (= 583mW EIRP or 355mW ERP)
> Reality : about 35mW ERP (based on field strength measurement)
> Difference : -10dB !
> Reason : antenna surrounded by many trees
>
> Maybe most other hams have more luck (less trees), but take into account
> that real ERP is 2 to 6dB below the calculated ERP.
>
> 73, Rik  ON7YD