Design of a compact microstrip triplexer for multiband applications

This paper presents a microstrip triplexer with multiband performances by using the simple cascaded resonators for reducing the circuit size. The three passband channels of the triplexer can be generated by using the stepped impedance resonators (SIRs) and the uniform impedance resonators (UIRs) when their fundamental and the higher order frequencies are properly assigned. The triplexer has only four simple resonators, thus the circuit size can be effectively reduced. Measured results of the proposed triplexer have a good agreement with the electromagnetic (EM) simulated results.