Design of compact microstrip diplexer with simple coupled resonators

This article presents a microstrip diplexer with 2.4/5.2 GHz response by using the simple coupled resonators for reducing the circuit size. Stepped impedance resonator (SIR) can be shared by the two filter channels for the designed diplexer if their fundamental and the higher order frequencies are properly assigned. The diplexer has only three simple resonators which can achieve both two good passbands and effectively reduce the circuit size. Measured results of the proposed diplexer have a good agreement with the electromagnetic (EM) simulated results. (c) 2007 Wiley Periodicals, Inc.