Abstract: On the basis of coupling double-gap cavities, a new multi-cavity filter with two-layer coaxial cavity cross-coupling is proposed in this paper. It utilizes the coupling coefficient analyzed by couplefilter software and the 3D simulation software HFSS procedures of modeling, simulation and optimization to realize the integral design of the two-layer coaxial cavity bandpass filter. Simulation results show that the performance of band width, out-band suppression and insertion loss of a two-layer filter with 4 cavities have the advantages of that of a single layer filter with 4 cavities. Such new filters with merits of wide frequency band width, satisfactory out-band suppression, compact structure and various shapes would better meet the requirements of microwave communication systems such as radar or mobile communication station.

Key words: coupling double-gap cavity; mobile communication station filter; metal cavity filter; two-layer coaxial cavity filter