小型化SIR同轴腔体双通带滤波器研究

Miniaturized coaxial dual-passband filters using stepped impedance resonator

基于频率变换技术的双通带滤波器综合理论,应用阶跃阻抗谐振器(SIR)的基本原理,在双通带滤波器设计中引入λg/4型SIR同轴腔体谐振单元,设计了一种交叉耦合型拓扑结构的小型化同轴腔体双通带滤波器,相比于实际长度λg/4的传统滤波器,尺寸压缩了约50%。仿真结果显示,两个通带内回波损耗均大于20 dB,插入损耗小于0.1 dB,通带之间的阻带衰减特性良好。该滤波器的两个传输零点提高了阻带抑制度,满足了通信系统对滤波器小型化、低插损、高选择性的要求,能够广泛应用于双频带通信系统。

Based on the synthesis theory of dual-passband filter（DPBF） with frequency transformation technique.λg/4 type SIR coaxial harmonic unit was introduced in the design of DPBF by using the basic principle of stepped impedance resonators, the miniaturized coaxial DPBF with cross-coupling topology structure was designed. As compared to the traditional filter withλg/4, the dimension was reduced almost 50%. The simulation results show that both return losses of two pass-bands are higher than 20 dB, while insertion losses are lower than 0.1 dB with its good attenuation characteristic between two pass-bands. The DPBF can generate two transmission zeros to increase the stop-band suppression, which fully satisfies the requirements of miniaturization, low insertion loss, high selectivity in communication systems. It can be widely used in dual-frequency communication systems.