Research And Design Of Metasurfaces For Antenna Radiation Control

In recent decades,new artificial electromagnetic metamaterials have been a key research topic.Among them,artificial electromagnetic surfaces,as two-dimensional artificial electromagnetic materials,have the advantages of small occupation space and low loss,and are easy to combine with traditional electromagnetic devices.hot spot of attention.In this thesis,several current mainstream artificial electromagnetic surface design methods are taken as research goals,and they are applied to the control of electromagnetic beams.Firstly,this thesis summarizes the performance of common artificial electromagnetic surface elements in terms of bandwidth and resonant frequency stability,and concludes that the ring-shaped and Jerusalem-type elements have better performance.Therefore,the opposite ring elements are combined to form the form of two-sided ring elements,and the optimization is carried out on the basis of the two-sided ring elements,and finally a new type of metasurface element is designed.For the new unit,we perform performance simulation tests in terms of transmission characteristics,polarization stability,and angular stability.After that,we analyze the surface electric field energy of the new unit when it works,obtain an equivalent circuit model of the unit,and analyze the influence of the unit size parameters on the equivalent surface impedance characteristics.According to the analysis results,we scan the geometric dimensions of the cells,and obtain the cell（meta）library of the new cells,which is equipped with a meta search algorithm.Then we analyzed the design method of artificial electromagnetic surface,and found that many scenarios need to design artificial electromagnetic surface according to the transmission field outside the electromagnetic surface and the known incident field inside the surface,that is,the idea of generalized boundary transmission condition.Regarding the transmission field outside the surface,we need to calculate and obtain it according to the actual target far field,so we use the electromagnetic surface integral method and the moment method to construct a matrix equation of the relationship between the target far field and the surface electromagnetic current,and use the conjugate The gradient-leastsquares iterative algorithm solves the equation to obtain the distribution of surface electromagnetic currents.In order to verify the accuracy of this field source reconstruction algorithm,we used the medium scattering and antenna radiation as the verification scenarios,and compared the actual far field and the far field generated by the reverse source,and found that the results were very consistent.Finally,we combine the design and practical application of artificial electromagnetic surfaces.First,a phase compensator for microstrip antennas is designed based on the Huygens principle for complete control of the transmission phase,which realizes the conversion of spherical waves to plane waves and improves the far-field beam directivity of ordinary microstrip antennas.Then,according to the generalized Snell’s law and Huygens principle,a beam deflection lens is designed,which realizes the large-angle deflection of the electromagnetic beam.Finally,the beam deflection lens is redesigned according to the GSTCs method,which is different from the deflection lens designed by generalized Snell’s law.We first use the field source reconstruction algorithm to convert the target deflection far field into an artificial electromagnetic surface.The tangential field of the surface,and then design our artificial electromagnetic surface according to the known incident field.Finally,we combine the design and practical application of artificial electromagnetic surfaces.First,a phase compensator for microstrip antennas is designed based on the Huygens principle for complete control of the transmission phase,which improves the far-field beam directivity of ordinary microstrip antennas.Then,according to the generalized Snell’s law,a beam deflection lens is designed to achieve a certain angle deflection of the electromagnetic beam.Finally,according to the field source reconstruction algorithm and the GSTCs method,the deflecting lens metasurface is designed,and the real object is processed for testing and verification.