inductance of a triaxial cable

[myoung7]

Hello, I'm a new member of the forum.

Are there any good sources of information available that contain (and explain) inductance calculations for various symmetrical (but unconventional) geometries? I'm interested in a triaxial conductor that is similar to a coax in geometric make-up, but there are three concentric cylindrical conductors instead of two. I know that triaxial cables exist (mostly for small signal high frequency apps), but I cannot find any theory about them in books or journals. If someone in this forum can help me or point me in the right direction, I would deeply appreciate it.

Thanks,

Marcus

[mmwave]

For a start, the inductance on the innermost conductor should not change in triax, so the reference books will help you there - just treat it like coax.

Typically, the outermost conductor is grounded to act as a shield. The presence of the ground surrounding the second conductor will affect its inductance. I've never seen such a calculation and I never seemed to need know this when I've used triax. What mattered to me was the impedance between the innermost & second conductor.