基于折叠短截线耦合理论的新型宽带带阻滤波器设计

Design of a Novel Wideband Bandstop Filter Based on Coupling Theory of Folded Stubs

提出一种新型的基于折叠短截线耦合理论的宽带带阻滤波器(BSF)设计方法。根据所提出的方法,设计了一款阻带范围可控、传输零点可控、阻带抑制良好的紧凑型宽带带阻滤波器。该滤波器分为上下两部分,上部分为对称的主传输线加载折叠短截线单元,下部分是由公共短截线拓扑而成的矩形贴片。可以通过改变短截线单元的间隙耦合和矩形贴片的长度来调节阻带抑制性能和阻带范围。所提出的宽带带阻滤波器的截止频率为2.04GHz,阻带中心频率为2.88 GHz,阻带范围为1.57~4.19 GHz,-3 dB衰减带宽达到90.9%。阻带内有三个可控的传输零点,并具有38 dB的良好抑制性能。-20 dB、-38 dB衰减带宽分别为50.3%(2.04~3.49 GHz)、36.5%(2.16~3.21 GHz)。实物测试结果与仿真基本一致。

A new type of bandstop filter(BSF)design method based on folded stub coupling theory was proposed. According to the proposed method,a compact wideband bandstop filter with controllable stopband range,controllable transmission zero point and good stopband suppression was designed. The filter is divided into upper and lower parts,the upper part is a symmetrical main transmission line loading folded stub unit,and the lower part is a rectangular patch formed by the common stub topology. The stopband suppression performance and stopband range can be adjusted by changing the gap coupling of the stub unit and the length of the rectangular patch. The cut-off frequency of the proposed wideband bandstop filter is 2.04 GHz,the center frequency of the stopband is 2.88 GHz,the stop band range is 1.57~4.19 GHz,and the-3 dB attenuation bandwidth reaches 90.9%. There are three controllable transmission zero points in the stopband,which has a good suppression performance of 38 dB. The-20 dB and-38 dB attenuation bandwidths are 50.3%(2.04~3.49 GHz)and 36.5%(2.16~3.21 GHz)respectively. The physical test results are basically consistent with the simulation.