Sixteenth-mode substrate integrated waveguide cavity filters

摘要

This paper presents bandpass filters using sixteenth-mode substrate integratedwaveguide (SMSIW) cavities operating at fundamental mode TM010. The first filteris a single-layer fourth-order bandpass filter which exhibits compact size, goodselectivity and wide-stopband up to 2.25f0. The stopband rejection is restricted dueto the presence of the passband generated by the higher-order mode TM020. To furtherreduce the size and improve the stopband characteristic of the filter, a multilayerconfiguration is proposed. The second filter is a multilayer second-orderbandpass filter in which the two cavities are coupled through a circular arc-shapedslot etched on the ground plane of the cavities. The position and the dimensions ofthe slot are adjusted to obtain the desired couplings of TM010 and TM020 modes.The passband is created by TM010 mode, and its bandwidth can be controlled byrealizing the desired TM010 coupling. Moreover, the passband constituted byTM020 mode is suppressed by minimizing the coupling of TM020 mode, and a stopbandup to 3.14f0 is obtained which is wider than that of the first filter. The proposedfilters have the advantages of compact size, low loss, and wide-stopbandperformance. The filters are designed, fabricated and measured. The simulation andmeasurement results show an acceptable agreement.