Application Of Scattering Parameters Method In Electromagnetic Homogenization Of Two Dimensional Metasurface

With the development of information technology,many kinds of wireless communication applications are integrated into a single mobile terminal,such as Wi-Fi,GPS,NFC,cellular communication,Bluetooth and so on.It demands that antenna can operate at multibands.There are many ways to make antenna operate at multiband.In this paper,we design the frequency reconfigurable antenna based on two-dimension metasurface,so as to discuss electromagnetic homogenization problems of the two-dimension metasurface.Metamaterials are new materials made up of artificial structures,and they have some special physical properties that natural materials do not possess.We made metasurface by three-dimension metamaterials.Compared with three-dimension metamaterials,metasurface have merits such as small volume and light weight.Duplicating the artificial unit periodically or non-periodically,we can get metasurface with special electromagnetic properties.The operating frequency,polarization and radiation patterns of antenna can be controlled while we put the metasurface on it.A slot microstrip antenna working at C waveband is proposed in this paper.We designed four kinds of metasurface,i.e...line-metasurface,ellipse-metasurface(AR=10,AR is short for axial ratio),ellipse-metasurface(AR=3)and circle-metasurface that can realize antenna with frequency reconfiguration abilities.We put metasurface on the antenna directly,and antenna working frequency can be reconfigured by rotating the metasurface to change their relative position.Simulation results of the operating frequency ranges of the antennas based on four kinds of metasurface can be achieved by CST microwave studio.The central operating frequency ranges of line-metasurface,ellipse-metasurface(AR=10),ellipse-metasurface(AR=3)and circle-metasurface are 958 MHz,808MHz,660 MHz,96MHz.We manufacture the prototypes of the proposed ellipse-metasurface(AR=3),slot microstrip antenna and line-metasurface and measure them in microwave echo chamber.After comparing the measured result with the simulation result,we found that they match each other well.The reason why we can realize frequency reconfiguration is that the relative permittivity and the relative permeability changes after rotating the metasurface.We use the Nicolson-Ross-Weir method(NRW)to homogenize the electromagnetic parameters of metasurface.Firstly,we simulated unit cells and got S-parameters of the unit.Then,we used the S-parameter in NRW to derive relative permittivity and relative permeability of the metasurface units.Finally,equivalent dielectric substrate models with relative electromagnetic parameters of metasurface were built and we simulated them after putting the models on the slot microstrip antenna respectively.After comparing the results of equivalent models and actual models,they matched well.