Design procedure of wideband band-pass filter consists of inter-digital finger resonator and parallel coupled lines

The design procedure of a wideband band-pass filter (BPF) which consists of an inter-digital finger resonator and parallel coupled lines is proposed in this paper. The design of the bandwidth was described by using the even and odd mode characteristic impedances in the resonator structure. The parallel coupled line was also analyzed in the same manner. The parameters of those elements in combination as the BPF were then optimized by the simulation. The designed BPF was experimentally fabricated and its measured performances showed the bandwidth from 3.6 to 10 GHz with the 20 dB outband rejection.