微带SIR带通滤波电路寄生通带的分析

本文分析微带SIR（阶梯阻抗谐振器）带通滤波电路的寄生通带问题。这种滤波器的特点是其寄生响应时以通过阻抗比K进行控制，因而增进了谐波抑制性能。SIR可以采用等电长度或非等电长度。等电长度SIR滤波电路的第三寄生通带的带宽来零，然而，非等电长度SIR滤波电路却增加了设计的灵活性，分析与探讨微带SIR滤波电路的寄生带通问题，对于合理设计与应用这种滤波电路是有益的。

Analysis for Parasitic Passband of Microstrip SIR Bandpass Filters

The parasitic passband of microstrip bandpass filters using parallel coupled SIR (Stepped Inpedance Resonators) is analyzed in this paper. A prominent feature of this filter is that the spurious response can be controlled by the impedance ratio K of the resonator, thereby the performance for harmonic suppression is improved. Either equal or non-equal electric length can be used for SIR. The bandwidth of the third spurious response of filter with equal length is zero. Taking advantage of the filter based on non-equal length SIR, flexibility in design process can be increased. Analysis and Discussion concerning parasitic bandpass is useful in the application of microstrip SIR bandpass filers and beneficial to their design procedure.