基于电磁混合耦合的SIW宽阻带带通滤波器设计

Design of SIW Wide Stopband Bandpass Filter Based on Electromagnetic Hybrid Coupling

为实现阻带一段范围内依然具有良好的抑制能力,提出了电磁混合耦合的基片集成波导(Substrate Integrated Waveguide,SIW)宽阻带带通滤波器(Bandpass Filter,BPF)。根据模式的本征抑制和电磁混合耦合理论,合理地设置外部馈电端口、内部耦合窗口及内部耦合圆孔阵列,抑制了频率低于TE_(105)和TE_(501)之前的所有高次模,并且使得工作模式TE101电耦合很好地传输。仿真与实测结果均显示,该滤波器的中心频率f_(0)=5.94 GHz,插入损耗为−3.46 dB,相对带宽为2.44%,当阻带宽度延伸至3.85 f0时,抑制深度优于20 dB。与经典的四阶SIW宽阻带带通滤波器相比,拥有相同的带宽时,该双层层叠的方式更加紧凑,有利于集成到微波电路系统中。

A substrate integrated waveguide(SIW)wide stopband bandpass filter(BPF)with electromagnetic hybrid coupling is proposed to achieve good suppression within a stopband range.According to the theory of mode intrinsic suppression and electromagnetic hybrid coupling,the external feed port,the internal coupling window and the internal coupling circular hole array are set reasonably,so that all the high-order modes with frequency lower than TE_(105)/TE_(501)are suppressed,and the electrical coupling of the working mode TE101 is transmitted well.Both simulation and measured results show that the center frequency f0=5.94 GHz,the insertion loss is-3.46 dB,and the relative bandwidth is 2.44%.When the stopband width extends to 3.85 f0,the suppression depth is better than 20 dB.Compared with the classical fourth-order SIW wide-stopband bandpass filter,the double-layer stacked method is more compact when having the same bandwidth,which facilitates the integration into microwave circuit system.