在传统1/4波长阶跃阻抗谐振器（step impedance resonator, SIR）的基础上，提出一种新型双频宽带带通滤波器(bandpass filter,BPF)的结构及其设计方法，其中心频率为1.90/5.65 GHz，可工作于GSM等无线通信系统中.该滤波器频率覆盖范围广，带宽宽，其第一频段的绝对带宽为980 MHz，第二频段的绝对带宽为960 MHz.该滤波器在基频1.90 GHz的回波损耗低于-25 dB，插入损耗为-0.012 dB.同时，滤波器的两通带隔离度好，结构简单，易于加工.频率响应特性S₁₁和S₂₁的电磁仿真和实测结果非常吻合.

Based on the traditional quarter wavelength step impedance resonator (SIR), a new dualband bandpass filter (BPF) with wide bandwidth is proposed. Its center frequencies are 1.90/5.65 GHz, which can be used in wireless communication systems such as GSM. The filter has a wide frequency range, with the absolute bandwidth of the first and second center frequencies being 980 and 960 MHz respectively. At  1.90 GHz, the proposed BPF has return loss less than -25 dB and insertionloss less than -0.012 dB. The BPF has better isolation between the two passband and a simple structure for easy manufacturing. Simulated frequency responses S₁₁ and S₂₁ of the filter agree with the measured results.