[TowerTalk] inductance of tubing vs bar or strip

[Jim Brown]

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