This paper is dedicated mainly to the study of couplings between planar resonators in multilayer structures with modified (defected) ground plane. Couplings between two miniaturized resonators are investigated, by full electromagnetic field simulation. Based on the results of this study, several models of planar microwave bandpass filters, with a single or with two apertures, are designed, verified by simulation, fabricated and measured. Compared to the classical filters, these novel structures show a good compactness and can offer some technological advantages.

Keywords: Microwave, Filter, Multilayer, Resonator, Cross-coupling.