基于人工表面等离子体激元高阶模式的带通滤波器

Bandpass Filter Based on High-Order Mode of Spoof Surface Plasmon Polaritons

基于人工表面等离子体激元(SSPPs)的一阶高次模,设计了一种具有优异带通性能的滤波器。所采用的SSPPs单元结构为类八木天线结构,该结构可以有效降低SSPPs的渐近频率。此外,通过改变SSPPs单元结构的几何参数,可独立控制其渐近频率和与自由空间中光线的交点频率。与具有低通特性的SSPPs基模相比,一阶高次模具有天然的带通特性,且不需要采用额外的阶梯渐变过渡结构。为了验证SSPPs高阶模式应用于带通滤波器设计的可行性,制作并测量了基于该方法的SSPPs滤波器。测试结果表明,该滤波器在6~9.9 GHz的通带频率范围内的插入损耗小于1 dB,带内回波损耗优于10 dB,实验结果与仿真结果具有良好的吻合度。

A bandpass filter is proposed in this paper by utilizing the high-order mode of spoof surface plasmon polaritons(SSPPs).The adopted SSPPs unit cell is a Yagi-like antenna structure,which can effectively reduce the asymptotic frequency of the SSPPs.In addition,the asymptotic frequency of the mode 1 and the intersection frequency with the light line in free space can be manipulated by adjusting the geometric parameters of the SSPPs unit cell.Compared with the fundamental mode with low-pass characteristics,the mode 1 has inherent band-pass response and does not require an additional gradient transition structure for excitation.In order to verify the feasibility of proposed high-order mode based bandpass filter,a topology is fabricated and measured by the vector network analyzer.The measured results show that the insertion loss is less than 1 dB from the frequency range of 6 GHz to 9.9 GHz,and the in-band return loss is better than10 dB,which is in agreement with the simulated ones.