Superconducting electrically-small dipole antenna

A superconducting electrically-small dipole antenna was constructed and compared with a copper antenna of similar dimensions, both operating at low VHF frequencies. The antennas had lumped inductive loading to ensure that the feeding network was also electrically small. The superconducting antenna was formed from high-T_c ceramic superconductor and was parasitically driven in order to avoid problems of electrical (YBa₂Cu₃O_x) contact to this material. Both antennas were tested by immersion in a bath of liquid nitrogen in an electromagnetically-transparent container. The superconducting antenna achieved a higher Q-factor than the copper equivalent, the Q-factors being about half the values expected from simple theory. The efficiency of the superconducting antenna was also deduced to be about double that of the copper antenna