[TowerTalk] inductance of tubing vs bar or strip

[Richard (Rick) Karlquist]

Steve, W3AHL wrote:

> No, you can't just multiply the inductance of one foot of wire by ten to 
> find the inductance of 10'.  Use the calculator.

Can you give us more details on what you mean here or a citation
from a text book?  AFAIK, inductance is proportional to length,
assuming the whole length is the same distance from ground, as long
as the length is small compared to a wavelength.  (~10% error
at 1/10 wavelength).

> 
> The inductance of both round and strip conductors increase as they approach 
> a ground plane or other conductors.  So the free space inductance given by 

No, it's the other way around.  Inductance decreases as the conductor
approaches the ground plane.  This is because the enclosed area
of flux is smaller.

Rick N6RK