Reconfigurable Multiband Bandpass Filters in Evanescent-Mode-Cavity-Resonator Technology

The development of 3-D reconfigurable microwave multiband bandpass filters in substrate-integrated evanescent-mode-cavity-resonator technology is presented. The proposed filter approach exploits multiband quasi-bandpass sections whose tunable resonators do not directly interact with one another. In this manner, a multiband filtering transfer function with independently frequency-controllable passbands and interband transmission zeros is realized. Moreover, the number of active passbands can be dynamically selected in this filter architecture through their spectral merging as well as their intrinsic switching-OFF through resonators' detuning. These operational capabilities are theoretically demonstrated by means of several coupling-matrix-level synthesis examples. Furthermore, for experimental-validation purposes, a triple-band second-order prototype with three electronically tunable transmission bands in the range 2.2-2.8 GHz is designed, manufactured, and tested.