A Low-Loss Balanced Dielectric Strip Resonator Filter

In this paper, a low-loss balanced bandpass filter (BPF) based on half-wavelength dielectric strip resonator is proposed, which consists of a thin dielectric strip with high permittivity and a low-permittivity substrate with bottom ground plane. The dielectric strip is used to replace the metal strip of the traditional microstrip line. Since there is no induced surface current on the dielectric strip, the unloaded quality factor (Q(u)) of the proposed resonator can be improved significantly, especially at high frequency. Meanwhile, the proposed resonator can be easily excited by the differential tapped microstrip lines for constructing the balanced BPF because its odd symmetric E-field distribution is similar to the microstrip counterpart. A prototype of the balanced BPF is simulated to show the advantages of the dielectric strip resonator.