Dual-band filtering power divider with widely separated passbands

This article presents a dual-band microstrip filtering power divider with widely separated passbands. The design topology is mainly constructed by two pairs of dual-mode resonators, an open-ended input line and two T-shaped output lines. Owing to the field symmetry at the two sides of the input line, two identical signals are coupled to the resonators and finally transmitted at two output ports. Since each pair of the employed dual-mode resonators can be independently designed, widely separated dual-passbands response is specified and derived in this work with the even-mode/odd-mode analysis. Moreover, good isolation with wide isolated frequency band is realized by introducing resistors between each pair of resonators. To validate the design concept, a prototype centering at 2.39 and 3.83GHz is implemented following the given design procedure. Measured results of the fabricated circuit agree well with the simulated ones, exhibit high frequency selectivity, good port-to-port isolation, and port matching.