WAVEGUIDE FILTER WITH BROAD STOPBAND BASED ON SUGSTRATE INTEGRATED WAVEGUIDE SCHEME

摘要

A waveguide bandpass filter utilizing a substrate integrated waveguide (SIW)scheme is provided with wide stopband performance and low in-band insertionloss atmicrowave and millimetre-wave frequencies. The filter consists of cascadedoversized substrateintegrated waveguide cavities, and at least one transmission line of eithermicrostrip, stripline orcoplanar waveguide with coupling slots is used as the input/output. Thetransmission zerosgenerated by the non-physical cross-couplings through the higher-order modesin the oversizedsubstrate integrated waveguide cavity are assigned to improve the stopbandperformance. Thisfilter is very easy to integrate with planar circuits for microwave andmillimetre-waveapplications. Three typical implementations of this filter are illustrated ona general dielectricsubstrate using linear arrays of metallised via holes by a standard PCBprocess. These threetypical implementations operate at a center frequency of 20.2 GHz, althoughother centerfrequencies, such as approximately 5 GHz to approximately 60 GHz, areachievable.