Aperture Couplings inMultilayer Filtering Structures

Abstract-Inmultilayerstructures apertures in metallicsheets can betweenresonators. Having small sizes, these apertures exhibitbe used as coupling elements between resonators located on resonant frequencies far above the filter's passband, with different layers, allowing very compact filter designs. In this practically no influence onthe electrical responses in the band paper, some novel types of planar microwave bandpass filters, of interest. using aperture couplings, in structures with three metallic layers, configuration of a resonator coupled to its 50Q are considered. Couplings between two miniaturized resonators t ... areinvestigated, byfull electromagneticfield simulation. Basedon mTcrostrip feed lneis shownin Fig. . 1..the results of this study, several models of planar microwave The geometries of the investigated couplings between twobandpass filters, withasingle orwithtwoapertures, are designed, identical hairpin resonators are plotted in Figs. 2-5.verified bysimulation, fabricated