Compact dual-band bandpass filter using simply hybrid structures

Abstract

A novel compact dual-band bandpass filter (BPF) using a hybrid structure of microstrip patch and coplanar waveguide (CPW) is proposed, designed, and implemented. The dual-band response can be realised by embedding two CPW structures in the microstrip square patch, which can not only disturb two fundamental degenerated modes, TM100 and TM010, but also adjust the resonant frequency of the TM110 mode. The two degenerated modes are used to form the first passband while the TM110 mode and two CPW resonators are used to generate the second passband. The first and second passbands have two and three poles, respectively. The dual-band BPF has a simple structure and good performance.