Miniaturized 3 GHz cross-coupled planar microwave filters

Abstract

Cross-coupled planar microwave filters were fabricated using YB2Cu3O7-delta superconducting thin films deposited on both sides of a LaAlO3 single crystal substrate by pulsed laser deposition. The hairpin resonator geometry allows one to miniaturize the 3-GHz filters by compacting the entire filter onto a substrate with dimensions 0.5 cm x 1 cm. By adjusting the relative spacing among the resonators to establish adequate couplings, filters with very sharp rejection skirt and extremely small insertion loss in passband were obtained.