Dual-mode elliptic-function bandpass filter usingone single patchresonator without coupling gaps

A novel dual-mode, compact, and simple elliptic-function bandpass filter structure without coupling gaps is proposed. This filter has insertion loss < 1.5 dB and return loss > 10 dB within 2.3–2.375 GHz. Without coupling gaps between the feed lines and the patch resonator, the new filter can provide a low insertion loss and reduce uncertainty in fabrication.