Chris,
the values are measrued with antenna in resonance, so they are "ohmic".
It is the sume of all kind of losses (soil, greenery, coil) and (almost
neglectable) the radiation resistance.
73, Rik ON7YD
________________________________________
Van: [email protected] [[email protected]]
namens Chris Trayner [[email protected]]
Verzonden: woensdag 24 februari 2010 17:23
Aan: '[email protected]'
Onderwerp: RE: AW: LF: VLF_8.79 kHz_grounding systems
Hi Rik and others,
Thanks for your contribution.
> if using a short vertical monopole antenna at 9kHz a ground loss of more than
> 1000 Ohm seems quite realistic to me.
"Ground loss" at my QTH:
500kHz = 35 Ohm
137kHz = 130 Ohm
Do you mean resistance in the strict sense, i.e. the resistive component of
impedance; or in the rough sense, i.e. the ratio between voltage and current,
which is actually the modulus of impedance?
I ask because there are capacitance and capacitance-like effects in the ground.
If you are looking at (in effect) a resistance in series with a capacitance,
that could explain the 1/f effect.
Regards,
Chris G4OKW
PS - more details can be found in Keller, G.V. & Frishcknecht, F.C. /
Electrical Methods in Geoprospecting / Pergamon (1966). See in particular chap
1 - or probably skim it, as it is detailed and can get a bit boring. Pp. 43-55
talk about these capacitive-like effects. The size of the 'capacitance'
(capacitance, not its reactance!) even varies with frequency. If you look at
the graph on p.52 you may need to reach for a bottle of the strong stuff ;-)
-----------------------
Dr Chris Trayner
School of Electronic & Electrical Engineering,
The University of Leeds,
Leeds LS2 9JT, United Kingdom
Tel: +44 113 34 32053
Fax: +44 113 34 32032
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