近年来,多层结构的基片集成波导(SIW)带通滤波器因其结构紧凑的优点得到研究者们的青睐,与此同时,阻带带宽窄的缺点又阻碍了滤波器的发展。为了提升滤波器的阻带性能,提出一种基于多层结构的宽阻带SIW带通滤波器。将滤波器的内外耦合窗口设置在模式的最弱电场处,从本质上抑制该模式。同时引入电磁混合耦合理论,分析特定模式的电磁分布情况,并根据HFSS软件提取的耦合系数设计耦合孔径的大小和位置,实现对特定模式的抑制。仿真结果显示可以完全抑制谐振频率低于TE303模以内的所有高次模。实际加工并测量了该滤波器,中心频率为5.9 GHz,相对带宽为2.54%,阻带可以延伸至17.42 GHz (2.95f0 ,f0为滤波器中心频率),且带外抑制优于28 dB,仿真和测量结果显示两者吻合度较好。与其他SIW 滤波器相比,该方法设计简单、带宽可调、阻带更宽,易于应用到实际的微波通信系统中,具有潜在的应用价值。

In recent years, the multilayer substrate integrated waveguide (SIW) bandpass filter has been favored by researchers because of its compact structure. At the same time, The disadvantage of narrow stopband bandwidth hinders the development of the filter. In order to improve the stopband performance of the filter, a wide stopband SIW bandpass filter based on multilayer structure is proposed. The internal and external coupling window of the filter is set at the weakest electric field of the mode to inhibit the mode essentially. At the same time, the electromagnetic hybrid coupling theory is introduced to analyze the electromagnetic distribution of the specific mode, and the size and position of the coupling aperture are designed according to the coupling coefficient extracted by HFSS software to realize the suppression of the specific mode. The simulation results show that all higher order modes with resonant frequencies below TE303 can be completely suppressed. The filter is actually processed and measured. Its center frequency of the filter is 5. 9 GHz, its relative bandwidth is 2. 54%, its stopband can be extended to 17. 42 GHz (2. 95f0, f0 is the center frequency of the filter), and its out-of-band rejection is better than 28 dB. The simulation and measurement results show that the two are in good agreement. Compared with other SIW filters, the proposed method has the advantages of simple design, adjustable bandwidth and wider stopband. It is easy to be applied to practical microwave communication systems and has potential application value.

TN952