Multilayer quad-band BPF with controllable transmission zeros

This paper proposes a stacked stepped impedance resonator (SSIR) structure for designing compact quad-band bandpass filters (BPFs). The multilayer resonator structure is used to miniaturize the filter size. Moreover, its resonant frequency is determined by carefully designing the metallic pattern on each layer. Furthermore, a novel technique has been developed to create a pair of controllable transmission zeros on both side of each passband.