That's why I posted some actual measurements early on in this thread. I
couldn't find a model for a inductance of "straight wire over lossy earth".
The absolute accuracy of my quick tests probably aren't up to lab standards,
but the relative comparisons are, for the specific set-up I used at least.
A lossy ground plane just shows less increase in inductance than a perfect
ground plane.
Steve, W3AHL
----- Original Message -----
From: "Jim Brown" <jim@audiosystemsgroup.com>
To: "Tower Talk List" <towertalk@contesting.com>
Sent: Wednesday, August 19, 2009 3:53 PM
Subject: Re: [TowerTalk] inductance of tubing vs bar or strip
> On Wed, 19 Aug 2009 15:30:53 -0400, Steve, W3AHL wrote:
>
>>The formula and results used in the original stripline over ground
>>plane calculator I linked to agree with the three reference books I
>>have access to.
>
> Yes, BUT -- a conductor in free space and a conductor over lossy
> earth are rather different from stripline (a conductor over over
> ground plane, which is assumed to be highly conductive and
> lossless). The equation for stripline also assumes that the ground
> plane under the conductor is the return for signal current -- that
> is, the circuit forms either an inductive loop (low frequencies) or
> a transmission line (higher frequencies) with the ground plane.
>
> Remember that lossy earth has both resistance and a dielectric
> constant. Changes the problem (and the resulting equations) a bit.
> :)
>
> 73,
>
> Jim Brown K9YC
>
>
>
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