"Cecil Moore" wrote
My "Electronics Equations Handbook" gives the specifications
for a "SINCLE-WIRE ABOVE-GROUND TRANSMISSION LINE" including
Z0, C, L, and resistivity adjusted for frequency.
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Single-wire lines -

Primary Constants :
The single conductor has resistance and inductance.
Resistance includes radiation resistance.
Space and its contents has permittivity, permeability and conductance.
The 'return path' is space and whatever it contains.

Secondary Constants :
Phase shift and propagation velocity.
Attenuation (loss).

All parameters obey the classical mathematical rules of Maxwell and
Heaviside.

There are also, very common, 2 and 3-wire (3-phase) transmission lines
which have smaller radiation resistances, but radiation resistances
they DO have depending on conductor spacing.
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Reg.