Gg. Cook et al., IMPROVING EFFICIENCIES OF SUPERDIRECTIVE ARRAYS OF MONOPOLES OVER LOSSY GROUNDPLANES BY USING SUPERCONDUCTING DISC OVERLAYS, IEE proceedings. Microwaves, antennas and propagation, 142(6), 1995, pp. 462-466
Electrically small perfectly conducting superdirective monopole arrays
above lossy metal groundplanes are analysed at 5000 MHz using a momen
t method incorporating Sommerfeld terms. It is shown that significant
improvements in efficiency are obtained when small perfectly conductin
g discs, which can be realised using high-temperature superconductors,
are attached to the monopole bases, compared with the monopoles being
directly connected to the groundplanes.