Compact and switchable dual‐band bandpass filter with high selectivity and wide stopband

A compact and independently switchable dual‐band bandpass filter is presented. To achieve high selectivity response, transmission zeros beside the two passbands are generated due to crossed coupling. On the other hand, the use of quarter‐wavelength stepped‐impedance resonators can not only miniaturise circuit size but also widen the stopband by arranging the resonant frequencies in a stagger with the same fundamental frequency. The pin diodes are loaded at the end of the resonators as the switching devices to independently control each passband.