Supergain printed arrays of closely spaced dipoles made of thick film high-Tc superconductors

Closely spaced dipoles in an array configuration, if properly excited, may result in end-fire superdirectivity. Albeit at the expense of transmission bandwidth and radiation efficiency. Efficiency of superdirective arrays can be considerably improved if a high-T_c superconductor (HTS) is used in the realisation of the radiating elements and the feeding and matching network, resulting in practical supergain radiators. Basic feeding configurations, which in printed dipole arrays may induce superdirective excitation, an explored and characterised in terms of their efficiency and bandwidth. Superdirective and supergain array designs, operating at frequencies around 1 GHz, made of thick film YBa₂Cu₃O_7-x on yttria stabilised zirconia (YSZ) substrates are demonstrated. Their measured end-fire gains exceeded that of similar cryogenically cooled thick film Ag arrays by 3-6 dB