一种具有谐波抑制特性的窄带带通滤波器设计

提出一种小型化带通滤波器结构及其设计方法．该滤波器具有良好的窄带滤波特性和高次谐波抑制功能，其高次谐波抑制特性由谐振加载耦合微带线结构所产生的多个传输零点来实现，其中心工作频率和带宽则由短路短截线特性决定．基于传输线模型和奇偶模分析推导的解析设计公式使得该滤波器的设计变得简单而快捷．采用这种方法研制了一个中心频率为2.4 GHz的窄带带通滤波器， 其3 dB带宽为300 MHz，通带最小插损为0.4 dB; 在二次、三次谐波频率上具有35 dB的衰减，而四次谐波的衰减也超过20 dB．

Design of a compact narrow band-pass filter with harmonics suppression

A compact narrow band-pass filter with a low insertion loss and multi-order harmonics suppression is proposed. The harmonic suppression is realized through transmission zeros of the parallel coupled lines loaded open-circuited resonator, and the filter passband characteristics are determined by the short-circuited stubs. By coupling of the transmission line model of this filter and even- and odd-mode analysis, the expressions for calculating element parameters are presented, and thus the design process in this paper is fast and accurate. Finally, a band-pass filter working in 2.4 GHz is developed. Simulation and measured results show that the passband insert-loss is 0.4 dB, that stopband attenuations at second and third harmonics frequency are more than 35 dB, and that stopband attenuations at fourth is about 20 dB.