Design Of Functionally Reconfigurable Lens Based On Polarization Conversion Metasurface

With the rapid development of the information society,people’s demand for rates of wireless communication is increasing.Since the popularization of 5G communication technology,the research on reconfigurable antennas has attracted widespread attention from scholars in related fields.In this paper,by loading suitable tunable devices on the polarization conversion Metasurface(MS),the reconfigurable transmissive MS is constructed based on its phase mutation and polarization conversion characteristics.Besides,the flexible phase encoding algorithm is combined to achieve the functionality of MS,which has great prospects in the communications and military fields.Firstly,the working mechanism and phase-control theory of the polarization conversion transmissive MS are studied.Starting from the polarization form of electromagnetic waves,the basic electromagnetic concepts of linear polarization,circular polarization and elliptical polarization are introduced.Aiming at the working mechanism of MS,the derivation process from the typical Snell’s theorem combined with Fermat’s theorem to the generalized Snell’s law is explained.Subsequently,from the perspective of the Fabry-Perot cavity theory,the physical process of the polarization conversion MS with metal gate was introduced,and the phase-control theory of the polarization conversion MS was derived based on the transfer matrix and the matrix rotation formula.In order to calculate the theoretical near-and farfield of phase encoding MS,the MS diffraction theory is introduced.They pave the way for the subsequent research work.Secondly,the design and optimization of 1-bit reconfigurable transmissive meta-atom are completed.Based on the phase-control theory of the transmissive linear polarization conversion MS,a 1-bit meta-atom with adjustable phase is designed based on the tunability of the PIN diode with bias voltage.At the same time,the robustness of the meta-atom about the PIN diode equivalent circuit parameters is analyzed in detail.Subsequently,the influence of diode feed vias and feed lines on the cross-transmission coefficient and phase of the metaatom were further considered,and corresponding structure optimizations were made for them.Finally,the reconfigurable MS antenna system is established and verified.The designed 1-bit reconfigurable polarization conversion meta-atom is periodically arranged to form a MS array,which is constituted of a reconfigurable MS antenna system by added a suitable feed source.At the same time,by rationally arranging the feed method between the PIN diode and the multi-output voltage control circuit,and designing the control circuit connection port at the edge of the MS array,the purpose of using the circuit to independently control the working status of a single meta-atom in real-time can be achieved.In addition,in order to verify the functionality of the proposed reconfigurable MS antenna system,three simulations including multi-beam generation,vortex wave generation,and helico-conical beam generation were made.The theoretical electric field calculated based on the diffraction theory using 1-bit phase distribution is compared with the HFSS simulated electric field,which show a good agreement.