基于多模谐振器的陷波特性滤波器设计

Design of filter with notch bands based on multi-mode resonator

为了满足微波滤波器小型化要求,本文基于阶梯阻抗传输线(SIR)和加载短截线的方法提出了一种新型多模谐振器结构。同时,为了避免X波段卫星通信(7.9～8.395 GHz)对超宽带(UWB)系统造成干扰,本文设计了一款在8 GHz处产生陷波特性的UWB滤波器。此滤波器通过非对称耦合线的方式与所设计的新型多模谐振器形成交趾耦合来实现陷波,并且在上边频和下边频处产生了两个传输零点,提高了频率选择性。利用HFSS13.0仿真结果显示,该UWB滤波器的通带为2.98～11.12 GHz,相对带宽为115%,其陷波中心频率为8 GHz,陷波频段为7.75～8.41 GHz,插入损耗小于0.1 dB,实测与仿真结果基本吻合。该滤波器具有插入损耗小、体积小、带外抑制性能好的优点,可以应用到无线通信系统中。

In order to meet the miniaturization requirements of microwave filters,a novel multi-mode resonator structure was proposed based on stepped impedance transmission line(SIR)and stub-loaded.At the same time,in order to avoid the interference of X-band satellite communication(7.9-8.395 GHz)to ultra-wideband(UWB)system,a UWB filter with notch characteristics at 8 GHz was designed.The filter forms an intersection with the designed multi-mode resonator by the mean of an asymmetric coupling line to achieve the notch,and two transmission zeros are generated at the upper and lower side frequencies to improve the frequency selectivity.The simulation results of HFSS 13.0 show that the pass band of the UWB filter is 2.98-11.12 GHz,the relative bandwidth is 115%,the center frequency of the notch is 8 GHz,the notch frequency band is 7.75-8.41 GHz.and the insertion loss is less than 0.1 dB.The measured results are in good agreement with the simulation results.The filter has the advantages of small insertion loss,small size and excellent out-of-band rejection.It can be applied to wireless communication systems.