Compact UWB BPF with triple-notched bands based on stub loaded resonator

A compact ultra-wideband (UWB) bandpass filter (BPF) with triple-notched bands and wide stopband is presented. The basic UWB BPF comprises four folded shunt quarter-wavelength short-circuited stubs separated by connecting lines with lengths of λ_g0/4 and λ_g0/2, respectively. The proposed coupled triple-mode stub loaded resonator is found to have the advantage of introducing triple-notched bands simultaneously. Five stepped-impedance shunt stubs are chosen to suppress the harmonic passband. The predicted results are compared with measured data and good agreement is reported.