Electronics > RF, Microwave, Ham Radio

Common mode currents and double shielded coax

(1/2) > >>

A.Z.:

Folks, I'm banging my head about this, but can't reach an answer; I know about the three conductors in a coax and the CMC flowing on the outside of the coax braid, but ... what if we have a double shielded coax, where we have an external braid, insulator, an internal braid, center insulator and then center conductor, what happens to CMC then ? Could anyone here help this old brain sorting out this question ?

joeqsmith:
Same effect.  Common mode will want to be towards the outside. 

A.Z.:

--- Quote from: joeqsmith on May 20, 2022, 01:19:05 pm ---Same effect.  Common mode will want to be towards the outside.

--- End quote ---

yes, but the outside of... which braid ? With a dual shield coaxial we'll have 5 "conductors", the inner and outer surfaces of the outer braid, the inner and outer surface of the inner braid and the outer surface of the center conductor

joeqsmith:
Away from the center conductor.

A.Z.:

--- Quote from: joeqsmith on May 20, 2022, 02:29:32 pm ---Away from the center conductor.

--- End quote ---

As you wrote it, your reply makes little sense, but thanks anyway, found the answer myself; the CMC will flow on the outer shield of the external braid due to the skin effect which I didn't consider

Navigation

[0] Message Index

[#] Next page