A Novel and Compact Dual-Orthogonal-Ridged Dielectric Waveguide Resonator and Its Applications to Bandpass Filters

This article proposes and investigates a novel and compact dual-orthogonal-ridged (DOR) dielectric waveguide resonator (DWR) for the first time, where the two orthogonal ridges are set on the top and bottom surfaces of a traditional rectangular DWR, respectively. The proposed DOR DWR is theoretically analyzed and compared with the common dual-parallel-ridged (DPR) DWR. The comparison shows that the DOR DWR owns the merits of smaller size, higher quality factor, and farther harmonics simultaneously. To verify these advantages, two fourth-order Chebyshev bandpass filters (BPFs) operating from 2.515 to 2.675 GHz are designed and measured: one is designed by using the proposed DOR DWR and the other is based on the common DPR DWR for comparison. Of the two, the former is 34.6% smaller in size, 0.1 dB lower in insertion loss, and 25% extension in upper stopband as compared with the latter. Furthermore, the proposed DOR DWR is utilized to design a quasi-elliptic BPF based on the cascaded-quadruplet (CQ) coupling topology, and it is also measured. The measured results are in remarkable agreement with the simulated ones. In the measurement, the minimum in-band insertion loss is about 0.7 dB, the in-band return loss is better than 15 dB, and two transmission zeros (TZs) are produced at 2.38 and 2.79 GHz.