Study Of Manipulating Electromagnetic Wave Based On Optimization Algorithms And Metasurface

With the gradual improvement of electromagnetic theory,the technology of electromagnetic wave manipulation has also obtained great development.The regulation of electromagnetic wave is mainly aimed at the amplitude and phase of the beam.In this paper,the problems of the plane-wave synthesis,the beam deflector and the superlens are discussed.In the measurement of radiation and scattering,the plane wave is necessary to obtain the far-field radiation and scattering characteristics.Compared with the traditional method,the plane wave synthesis technology has more advances because of its high flexibility,small size and applicability for any frequency band.Combined with optimization algorithm,the method of near field has a good performance in plane wave synthesis.But the excitation network is much complex.The metasurface offers a new design concept for the electromagnetic wave manipulation devices.The arbitrary phase distribution can be precisely obtained by the macro sequence of subwavelength size metasurface.The low transmission efficiency and narrow band are two problems when designing a metasurface unit cell.The specific contents as follow:1.The plane wave synthesis technology in two and three dimension is studied based on the least squares method(LSM).The effects of the number of antennas on the plane-wave flatness is studied for the fixed-size area.The simulation results illustrate that the max amplitude error is less than 0.5dB and the max phase error is less than 5°.To further reduce the complexity of feed source network,the genetic algorithm(GA)is applied to optimize the excitation position and phase after selecting unit amplitude.Numerical examples confirm that the plane wave generation(PWG)excitation network can be simplified by the proposed procedure.2.A high efficiency dual-band metasurface is designed whose basic structureconsists of a complementary split-ring resonator(CSRR)and an electric-field-couple(ECL)resonator.The cross-polarization transmission efficiency is more than 0.7.As the basic pattern of the unit cell rotating,the cross-polarization abrupt phase shifts cover a 2? range under a circular polarization incidence.The phenomena of independent regulation at two frequencies is discussed.3.The beam deflector and the superlens are proposed based on the high efficiency dual-band metasurface.The results of the beam deflectors illustrate that the metasurface is polarization dependent,where the directions of the transmission waves are opposite when exciting left and right circle polarization wave,conformed to the General Snell's Law.Similarly,the numerical simulation results and the electromagnetic simulation software results indicate that the superlens acts as focusing lens when fed by LCPW at two frequencies,but acts as diverging lens when fed by RLCP.The polarization dependence of the deflectors and the superlens are proved.