Thz Graphene Hybrid E-Shaped Metal Patch Coding Metamaterials

The terahertz band can achieve ultra-wideband and ultra-high transmission rate communication^[1].The coding metamaterials are artificially designed subwavelength materials.The electromagnetic properties of the coding metamaterials can be controlled by artificial design,its ability of excellent control terahertz beam regulation has caused professional research^[2].In order to further promote the landing of coding metamaterials in terahertz communication technology,we innovatively explain the realization principle of polarization conversion from the perspective of phase characteristics.Based on the polarization conversion and Pancharatnam–Berry phase theory,we proposed an E-shaped metal patch coding metamaterials unit cell integrated with graphene.Combined with spatial impedance matching characteristics and coupling theories,we optimized the geometric parameters of the unit cell.We analyzed and extracted the characteristic parameters of the unit cell,and the unit cell can achieve polarization conversion in the frequency band from 0.35 THz to 1 THz（96.3%）,and the polarization conversion ratio（PCR）is more than 90%.When the incident angle of the terahertz waves changes from 0°to 20°,the electromagnetic characteristics of the unit cell is stable.We verified that the E-shaped metal patch coding metamaterials can effectively achieve RCS reduction.The main content of the paper is as follows:Firstly,we analyzed the theories of coding metamaterials.First,the unique physical properties of terahertz waves were introduced.Subsequently,the theoretical tools including the equivalent medium theory,generalized Snell’s law,the theory of phased array antennas and space-time coding metamaterials theory were researched.We analyzed the design and manufacture of coding metamaterials,at the same time,we introduced main application fields of terahertz technology.Secondly,we analyzed the commonly unit cells.We modeled and optimized the E-shaped coding metamaterials unit cell through CST Microwave Studio,analyzed and extracted the unit cell characterize parameters,including reflection amplitude and phase,polarization conversion ratio,the incidence angle influence characteristics of terahertz waves,current distribution characteristics at resonance frequencies,the multi-bit of the unit cells combined with Pancharatnam-Berry phase.Thirdly,we modeled the terahertz waves two-splitting array,four-splitting array and the 1-bit and 2-bit arrays of the RCS reduction through CST Microwave Studio,and we extracted the far-field characteristics and the near-field characteristics of these arrays.The RCS is reduced by more than 5 d B from 0.35 THz to 1 THz.Additionally,coding metamaterials unit cells based on rectangular and square metal patches were built.The coding matrix was established based on the terahertz waves of x-polarization and y-polarization.By optimizing geometric parameters of the unit cells through CST Microwave Studio,we filled this coding matrix.We built a coding array for terahertz waves polarization detection,and we verified the array can achieve polarization detection of 1.3 THz x or y polarization EM waves through the far-field characteristics.