Balanced Dielectric Resonator Filters With Multiple Reconfigurable Passbands

Balanced dielectric resonator (DR) filters with multiple reconfigurable passbands are proposed in this article. Based on the field distributions of two pairs of orthogonal degenerate modes, quad-mode differential-mode (DM) operations are achieved by the specific probe feeding structure. More importantly, the four modes are flexibly controlled by different inserted screws and the detailed principle is illustrated for reconfiguration. For demonstration, a dual-band balanced filter with independently frequency-tunable passbands and a quad-band one with selectable number of passbands are fabricated and measured. Good agreement between the simulated and measured results is observed. The exhibited low DM loss, high common-mode (CM) rejection, and independent tuning abilities verify the proposed method in miniaturized reconfigurable filter designs.