Design of microstrip bandpass filters with aperture coupled miniaturized hairpin resonators

Abstract

A four-pole elliptic function microstrip filter at 2.4 GHz with fractional bandwidth of 4% is realized using compact miniaturized resonators. The configuration of this filter consists of two back-to-back arrays of resonators on two dielectric layers. The common ground plane is located between the two layers. The signal in the upper dielectric surface can be coupled to the opposite side of the surface through the aperture on the common ground plane. The measured results show a good agreement with the simulation.