Pseudo-elliptic bandpass filters using closed-loop resonator

Abstract

2nd order pseudo-elliptic resonator topologies are presented in this paper. Based on the closed loop with coupled-line resonator, three 2nd order bandpass filter topologies were built. Each of these topologies offered pseudo-elliptic bandpass response with high selectivity that is suitable for RF and wireless applications. The main advantage of these topologies is that the structures were built from a closed-loop with coupled-line resonator which is easy to control to obtain desired electrical responses. To demonstrate the proposed concepts, the resonators were realized using microstrip technology and all the measurement results showing good agreement with those from the simulations.