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Re: LF: BODGE ANTENNAS

To: <[email protected]>
Subject: Re: LF: BODGE ANTENNAS
From: "Markus Vester" <[email protected]>
Date: Tue, 14 Dec 2010 21:42:25 +0100
Importance: Normal
References: <007901cb9bbf$2c223810$0401a8c0@xphd97xgq27nyf>,<[email protected]> <BF4A524700075746A6467658DFC7102C886FDD7539@ICTS-S-EXC2-CA.luna.kuleuven.be>
Reply-to: [email protected]
Sender: [email protected]
Yes Rik, theoretically the efficiency should be independent of soil resistivity:
 
Loss resistance ~ resistivity,
radiation resistance ~ area ^2 ~ skin depth ^2 ~ resistivity.
 
In practice the situation may be different, because the loss resistance occurs predominantly in the immediate vicinity of the earth contacts. The return current depth depends more on the large-scale ground properties, including deeper layers along the whole length of the antenna. In the ELF facilities, deep well grounding was used to minimize local current densities and potential gradients near the ends.
 
Best 73,
Markus (DF6NM)

 
Sent: Tuesday, December 14, 2010 9:11 PM
Subject: RE: LF: BODGE ANTENNAS

In my view it does work as a loop antenna on 136 and 500kHz with the loop area being determined by the soil conductivity (lower conductivity, bigger loop area).  The very fact that it is low-Q does suggest loss.
 
Hello Roger,
 
if 
low conductivity = large loop area (A) but small antenna current (I)
high conductivity = small loop area (A) but large antenna current (I)
Would this result in A*I = constant ?
 
The radiation resistance of a loop is proportional to the square or the loop area (A). And the ERP is proportional to the square of the antenna current (I).
If A*I is a constant (independent or soil conductivity) this would mean that the ERP would no depend on soil conductivity ?
 
73, Rik  ON7YD - OR7T 
 
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