IMPLEMENTING TRANSMISSION ZEROS IN INDUCTIVE-WINDOW BANDPASS-FILTERS

Transmission zeros are usually implemented in microwave filters as ext racted poles, or with cross couplings between nonadjacent cavities. Re cent work, however, indicates that, for inductive band-pass filters, h igher order-mode excitation can be usefully exploited for the purpose of creating transmission zeros, In this paper pie describe a new cavit y configuration that can be used to introduce transmission zeros in th e electrical performance of microwave filters based on thick inductive windows in rectangular waveguides using the higher order-mode interac tions, One transmission zero per filter cavity can be introduced and i ts frequency location can be easily controlled adjusting suitable geom etrical parameters, The basic principle is discussed in detail and a c omputer aided design procedure is also presented, Finally, several app lication examples are included indicating how the new cavity design ca n indeed be used to improve the performance of this class of filters.