Compact microstrip UWB bandpass filter with triple-notched bands and wide upper stopband

Abstract

A novel compact ultra-wideband (UWB) bandpass filter (BPF) with triple sharply notched bands and wide upper stopband is proposed. The basic UWB BPF is composed of two microstrip interdigital coupled lines and one multiple-mode resonator (MMR). Then, to achieve triple band-notched performance, the proposed triple-mode stepped impedance resonator (TMSIR) is studied and coupled to the interdigital coupled lines of the basic UWB BPF. To validate the design theory, a microstrip UWB BPF with three notched bands respectively centered at 5.2 GHz, 5.8 GHz, and 6.8 GHz is designed and fabricated. Both simulated and experimental results are provided with good agreement.