Design of a Novel Ceramic Dielectric Filter Based on Cross Coupling technology

A novel ceramic dielectric filter is proposed in this paper which based on cross coupling technology. By adjusting the relative depths of a pair of the side and the center blind hole, capacitive or inductive coupling can be achieved. This structure generates two out-of-band suppression zeros in the cascade quadruple (CQ) structure, thereby improving the frequency selectivity of the filter and enhancing its tuning accuracy. It meets the requirements of filter miniaturization and lightweight design. Based on this structure, a new six-cavity ceramic waveguide filter is designed to meet the needs of 5G base stations. The influence of the triple-blind-hole depth and the distance between blind holes on the coupling coefficient of the filter is analyzed in detail, and the corresponding variations are summarized. The simulation results are as follows: the center frequency is 3.5 GHz with the bandwidth of 200 MHz, the insertion loss ≤1.2 dB, the return loss ≥21 dB, and the frequency bands of 3.2-3.3 GHz and 3.7-3.8 GHz suppression ≥51 dB.