Miniaturized balanced bandpass filter using dual-mode dielectric resonator

This paper introduces, for the first time, a balanced dual-mode bandpass filter (BPF) using a compact rectangular dielectric resonator (DR), which is directly contact with the bottom of the metal cavity. The idea is to use the bottom metal plate of the cavity to replace the electric wall of the dominant modes, i.e., TE
^x
₁₁
and TE
^y
₁₁
, which are orthogonal to each other, of the rectangular DR, so as to keep the half field distributions of the two modes unaffected and the size of the DR becomes nearly half of the conventional one. The two half-cut modes can be used for constructing the differential-mode (DM) passband of a balanced dual-mode BPF. For demonstration, a balanced dual-mode BPF employing the proposed rectangular DR is designed and simulated, showing good DM and common-mode (CM) responses and offering a significant size reduction in comparison with the conventional DR filters.