Due to the frequency response's periodicity of distributed transmission line, microstrip bandpass filter usually produces parasitic passband and outputs harmonics away from the center frequence of main passband. Based on the study of traditional dumbbell defected ground structure, a novel DGS (Defected Ground Structure) and SISS (Step-Impedance Shunt Stub) structure having single-pole band-stop and slow-wave characteristics was presented to design a five-order microstrip low-pass filter. Eventually, the LPF was applied to a three-order coupled microstrip lines band-pass filter in order to improve its parasitic pass-band. The harmonics output was successfully suppressed and the cut-off frequency band was broadened by the verification of software simulation.%由于分布参数传输线频率响应的周期性,通常微带线带通滤波器在偏离主通带中心频率成分上会产生寄生通带,输出谐波.在研究经典哑铃DGS的基础上,利用新型DGS和SISS结构的单极点带阻和慢波特性,设计出五阶微带低通滤波器,并将之应用于三阶耦合线带通滤波器,改善其寄生通带.经过仿真验证,成功地抑制了三阶耦合线带通滤波器的谐波输出,拓宽了截止频带.
展开▼
