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A wide-stopband Wilkinson power divider with bandpass response and good isolation is presented. A 3-terminal, 2-pole bandpass filter and two 3-pole lowpass filters are used to replace the two quarter-wavelength transformer in a conventional Wilkinson power. The divider consists of two shorted-circuited half-wavelength stepped-impedance resonators and two 3-pole microstrip stepped-impedance lowpass filters. Thus, the divider achieves not only a bandpass response but also a very wide stopband. For the upper stopband performance, the rejection level is >10 dB up to 22.2 times the centre frequency.

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Distributed coupling technique and two pairs of stepped‐impedance resonators are used to realize a four‐channel diplexer. Due to the low loading effect of distributed coupling technique, the proposed circuit can design many channels without the use of complicated matching network. Each pairs of resonators is designed for a dual‐band performance achieving a compact size. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:166–170, 2016

Two switchable microstrip bandpass circuits are investigated. Owing to the low loading effect from the distributed coupling technique, many channels are obtained without a complicated matching network. Each passband can be turned on and off independently. Both the bandpass single‐pole quadruple‐throw switch and the switchable quadruplexer consisting of asymmetrical quarter‐wavelength resonators, shunt open stubs and p‐i‐n diodes feature compactness, high isolation and wide stopband. The isolation is better than 35 dB, and the 20‐dB stopband extends up to 13 times of the lowest operation centre frequency. To validate this design concept, theory as well as experiment are presented and compared.