Superconductors have been used as antennas where the gain has been
much much more than ham antennas. It does this by removing or
resisting the external magnetic field thus allowing the current flow
to exit the material and travel along its surface. Thus we are able to
reduce material
true resistance or losses and contribute solely to radiation.
By the same token, coils can be wound where it is totally resistive by
removing reactive forces. This also means the disappearance of skin
depth where the external magnetic field gains a foot hold. Thus, as
with a superconductor, we have removed the presence of resistive skin
depth resistance by allowing the current flow to exit the metallic
material and travel on its surface.
There are two resistances that must be dealt with in determining
efficiency where one is controlled by radiation that requires a equal
and opposite effect thus leaving only the metallic resistance to
concentrate upon
to increase efficiency. In both of the above cases we have been able
to divert current flow to the surface of the radiator to avoid the
intrinsic resistance of the radiating element, thus allowing all
alternating current flow to devote itself to creating radiation.
Art Unwin