Design of a novel compact wideband bandpass filter with shunt open-circuited stubs

A kind of novel compact wideband bandpass filter (BPF) is investigated in this paper. It is composed of four open-circuited stubs, in which two of them are folded to minimize the whole size of the filter. The new filter has been simulated and the characteristics are analyzed. The calculated results show that the BPF has a wide 3 dB fractional bandwidth which is more than 60% at the center frequency of 24 GHz. Besides, transmission zeros of the filter are very close to both sides of the passband to achieve a high selectivity. The filter is also fabricated and measured to demonstrate the performance, which shows good agreement with theoretical results.