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Re: AW: LF: VLF_8.79 kHz_grounding systems

To: [email protected]
Subject: Re: AW: LF: VLF_8.79 kHz_grounding systems
From: "Alexander S. Yurkov" <[email protected]>
Date: Wed, 24 Feb 2010 21:35:45 +0000 (GMT)
In-reply-to: <38A51B74B884D74083D7950AD0DD85E82A1B13@File-Server-HST.hst.e-technik.tu-darmstadt.de>
Reply-to: [email protected]
Sender: [email protected]
>  
> So, the coil losses decrease with it's L (assuming a given wire diameter, 
> coil diameter and spacing and so on) and thus it is good to decrease the
> needed L. 

You can decrease L only by condenser in parallel with a antenna.  But then
only part of coil current will flow thrue the ant (and ground stake also).
Let's describe some numerical example. Let antenna  capacity (denoted
as Ca) is 1 nF (large antenna!). Resistance of grounding we assume 1000
Ohm (huge resistance!). Parralel C (Cp) we assume to be 100 nF. Then L=3.2
mH. Let coil resistance is 1 Ohm (large coil!)  and coil current I is 1 A.
Then coil loss is 1 W. Antenna current for Ca<<Cp is (Ca/Cp)I = 0.01 A.
Grounding loss is (0.01)^2 * 1000 =0.1 W. With such a huge ground
resistance (unreally huge!) ground loss is only 10% of coil loss. 

Regards,
Alexander




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