基于近零介电常数超材料的液晶可调带通滤波器设计方法研究

Design of liquid crystal tunable bandpass filter based on epsilon near zero metamaterials

摘要:

可调带通滤波器是物联网、卫星通信、智能天线等系统中不可缺少的关键器件之一。针对目前对可调带通滤波器小型化、低成本和高集成度等特点的应用需求,提出了一种基于液晶材料的可调带通滤波器设计方法。通过微带传输线结构实现了近零介电常数(epsilon near zero,ENZ)超材料单元结构的设计,并利用ENZ超材料的窄通道隧穿效应有效实现了窄带滤波功能,通过将3个ENZ超材料单元结构串联从而完成了带通滤波器基本结构的设计。在此基础上,将微波液晶材料引入ENZ超材料的隧穿通道中,利用液晶材料在外部驱动电压作用下介电参数可变的特性,最终实现了对带通滤波特性的有效调控。全波数值仿真结果表明,所提出的基于ENZ超材料的液晶带通滤波器能够实现中心频率15.88~16.73 GHz的调控,从而验证了设计方法的有效性。

Abstract:

Tunable band-pass filter is one of the indispensable components in the Internet of Things, satellite communication, smart antennas. According to the current application requirements for miniaturization, low cost and high integration of tunable bandpass filters, a design method of tunable bandpass filters based on liquid crystal (LC) materials was proposed in this paper. Firstly, the epsilon near zero (ENZ) metamaterial unit based on microstrip transmission line structures was designed, and the narrow-band filtering function was effectively realized by the narrow-channel tunneling effect of ENZ metamaterials. On the basis of this, the bandpass filter consisted of three ENZ metamaterial units was designed to realize better filtering performance on this basis. Secondly, LC materials were introduced into the tunneling channel of ENZ metamaterials. The effective regulation of the band-pass filtering characteristics was finally realized by tuning the dielectric performance of LC materials with external driving voltages. Finally, the full-wave numerical simulation results showed that the proposed ENZ metamaterial-based LC bandpass filter could achieve continuous regulation of the center frequency from 15.88 GHz to 16.73 GHz, which verified the effectiveness of the above design method.