TWO NEW ELECTRIC COUPLING STRUCTURES FOR DOUBLE FOLDED SUBSTRATE INTEGRATED WAVEGUIDE CAVITY FILTERS WITH TRANSMISSION ZEROS

摘要

Two electric coupling structures for double folded substrate integrated waveguide (DFSIW) cavity filters are presented in this article. The coupling strength can be easily tuned, and the coupling mechanism is investigated. With electric coupling realized by the proposed structures in the main path and magnetic coupling by a conventional coupling structure in the cross coupling path, an X-band cross-coupled filter is designed, which possesses a transmission zero on either side of the passband. A prototype of the filter is fabricated to validate the predicted frequency response, and the measured results agree with the simulated ones.