A number of superconducting antennas have been built and the results
published. The ones I recall seeing were using the newer high
temperature superconductors, although it can be done with conventional
superconductors also.

It doesn't seem to be generally known that superconductors have zero
resistance only at DC. Their resistance is finite at any frequency above
zero. It increases with frequency, and it also increases as the
temperature rises toward the critical temperature (at which the material
ceases becoming a superconductor).

The resistivity of copper drops pretty dramatically at cryogenic
temperatures, so copper becomes pretty hard to beat at RF, particularly
if the temperature is getting anywhere near the critical temperature of
the competing superconducting material.

The potential advantage to be gained from a lossless antenna is that a
very small, efficient antenna can be made. The problems a

1. You have a really tough matching problem, and will have severe loss
in your matching network unless it's also superconducting.
2. If you do keep the antenna and matching network losses to a small
value, a very small antenna will be very narrow banded.
3. You'll have to keep the temperature far below the critical
temperature if you want to do much better than copper. This probably
means cooling to a few degrees Kelvin, which is expensive and not
compatible with putting antenna high and in the clear, let alone making
one that can be rotated, for example. And the advantage of a small
antenna is likely to be negated by the size of the cooling equipment.
4. Because the antenna will have finite resistance and presumably a
small size, application of transmitter power will cause heating. This
heat has to be removed by the refrigeration equipment to avoid raising
the temperature too much.

A google search on "superconducting antenna" will bring you a lot of
papers, but probably not much in the way of commercial products. While
interesting in the laboratory, the above problems limit the practicality
of the idea.

Roy Lewallen, W7EL

ml wrote:
i just wonder does anyone know of any links to articles on a small
superconducting antenna say for hf frequencies



what would happen if i build say i'd have to stay physically small , so
say a 1/4wave verticle on 10m and then made that antenna
supercondutive?

the antenna would technically have like no resistance that i know then
i get fuzzy


wonder what happens both technically speaking and if anyone tried it,
was it a 'great' antenna rx or tx wise?? any pro's con's of such a
design

aside from the obv cost and impracticaliaty of pumping Lhydr/liq helium
or nitrog into it etc