Design of a Metasurface Antenna Based on Characteristic Mode Theory

基于特征模理论的超表面天线设计

A novel metasurface antenna consisting of 5×5 rectangular patch elements is presented.Thestructure with and without the central element are both analyzed by the Characteristic Mode Theory(CMT).The developed mutually orthogonal principal modes of the optimized periodic patch structure areexcited by a center-feed dipole.A differential feeding network is employed to realize impedance matching.Prototype with profile height of 0.07λ_(0)(λ_(0)is the wavelength in free space at the lowest operatingfrequency)is fabricated and assembled to verify the simulation results.The measured results show that thereflectance coefficient of proposed matesurface antenna is less than-10 dB in the whole operating bandrange from 4.2 GHz to 5.5 GHz,a relative bandwidth of 26.8%is achieved,and the maximummeasured realized gain is more than 9 dBi with a maximum radiation efficiency of 90%.The designprovides a guideline on the application of characteristic modes(CMs)to radiation problems.

提出了的由5×5矩形贴片组成的超表面天线,通过特征模理论分析了中心单元存在和移除的场景。采用中心馈电的偶极子激励所需的相互正交特征模式,同时采用差分馈电网络实现阻抗匹配。对样机进行了加工组装,其剖面高度为0.07λ_(0)(λ_(0)是最低工作频率下自由空间波长)。仿真结果和实测结果表明,在4.2~5.5 GHz的整个工作频段范围内,所提出的超表面天线的反射率系数小于-10 dB,相对带宽达到26.8%,最大实测实现增益大于9 dBi,最大辐射效率为90%。该设计可为特征模在电磁辐射领域应用提供指导。