"art" wrote
I would also add that copper/braid itself does not turn into
a dielectric or contain a diode thus it also WILL also
pass a RF current at its centre but of course does NOT radiate.
_____________

art, you really need to buy and read Terman's RADIO ENGINEERS' HANDBOOK or
similar source, instead of relying on your intuition. Terman provides the
following equation for the r-f attenuation of air-insulated, copper coaxial
transmission line:

a = 0.00362 SQRT(f)*(1+ D/d) / D*log(D/d) dB per 1,000 feet

where f = frequency in MHz, D = inner diameter of outer conductor, d =
outer diameter of inner conductor.

Note that the attenuation is the same whether the inner conductor is solid
or tubular. This is the result of "skin effect," which for r-f frequencies
1.8 MHz and higher confines the r-f current on the inner conductor from its
outer surface to a depth of less than 0.18 mm.

RF