基于中心对称结构的带宽可重构滤波器设计

为适应需求日益复杂的无线通信环境，充分利用紧缺的频谱资源，设计实现了基于中心对称结构及变容二极管的电可调微带带通滤波器。通过电磁仿真软件HFSS进行仿真实验，在加载枝节的开口环谐振器结构上，引入叉指结构和马刺线型耦合馈线完成滤波器的原型设计。在原有的基础上加入可调节电容值的变容二极管，调节低频传输零点，实现通带带宽可重构，从而达到灵活控制滤波性能的目的。实际测试表明该滤波器的初始相对带宽为5.1%,初始绝对带宽为170 MHz,变容二极管调节绝对带宽在140～200 MHz范围内，即82.4%～117.6%,中心频率在2.70～2.76 GHz,传输零点调谐范围在2.57～2.63 GHz,通带内插入损耗在0.9～1.5 dB,回波损耗在10～35 dB,测试结果与仿真基本相符，在S波段的带宽精密控制方向具有一定应用前景。

Design of bandwidth reconfigurable filter based on centrosymmetric structure

In order to adapt to the increasingly complex wireless communication environment and make full use of the scarce spectrum resources, this paper designs and implements an electrically tunable microstrip bandpass filter based on centrosymmetric structure and varactor diodes. The electromagnetic simulation software HFSS is used to conduct simulation experiments. On the split ring resonator structure loaded with branches, an interdigital structure and a spur-shaped coupled feeder are introduced to complete the prototype design of the filter. On the basis of the original, a variable capacitance diode with adjustable capacitance value is added to adjust the low-frequency transmission zero point to realize the reconfiguration of the passband bandwidth, so as to achieve the purpose of flexibly controlling the filtering performance. The actual test shows that the initial relative bandwidth of the filter is 5.1%, the absolute bandwidth is 170 MHz, the absolute bandwidth adjusted by the varactor diode is in the range of 140~200 MHz, that is, 82.4%~117.6%, the center frequency is in the range of 2.70~2.76 GHz, and the transmission zero point tuning range is 2.57~2.63 GHz, the insertion loss in the passband is in the range of 0.9~1.5 dB, and the return loss is in the range of 10~35 dB. The test results are basically consistent with the simulation, and it has certain application prospects in the direction of precious bandwidth control in the S-band.