GRAPHENE BASED RIS FOR THZ WIRELESS COMMUNICATION

Abstract

FIGURE 1: SPECTRUM SHOWING THE TERAHERTZ REGION 8 FIGURE 2: META-SURFACE 25 FIGURE 3: GRAPHENE 27 FIGURE 4: POSSIBLE REAL-WORLD SCENARIOS OF THZ-ENABLED DRONE NETWORK 30 FIGURE 5: GRAPHENE DESIGN 36 FIGURE 6: UNIT CELL 36 FIGURE 7: SCHEMATIC OF THE GRAPHENE RIS SUBSTRATE 37 FIGURE 8: GRAPHENE UNIT CELL 40 FIGURE 9: S(1, 1) OF GRAPHENE PATCH 41 FIGURE 10: GRAPHENE BASED RIS WITH CIRCULAR PATCH 42 FIGURE 11: S (1, 1) PARAMETER 43 FIGURE 12: GRAPHENE BASED RIS PHASE RESPONSE 43 FIGURE 13: REFLECTION WITH DIFFERENT RADIUS OF GRAPHENE UNIT CELL 44 FIGURE 14: REFLECTION WITH DIFFERENT HEIGHT 46 FIGURE 15: PERFECT ABSORPTION AT1 THZ AND 2.85 THZ 48 FIGURE 16: VSWR 49 FIGURE 17: S(1, 1) OF METALLIC RIS 50 FIGURE 18: DESIGN OF 4X5 GRAPHENE BASED RIS 52 FIGURE 19: FAR FIELD 3D RADIATION PATTERN 53 FIGURE 20: FAR FIELD 1D RADIATION PATTERN @Θ=45 54 FIGURE 21: FAR FIELD 1D RADIATION PATTERN @Θ=60 55 FIGURE 22: FAR FIELD 1D RADIATION PATTERN @Θ=90 56 FIGURE 23: SNR 57 FIGURE 24: EQUIVALENT CIRCUIT MODE 58 FIGURE 25: CIRCUIT MODEL 61 FIGURE 26: S (1, 1) PARAMETER OF ADS MODEL 62 FIGURE 27: S PARAMETER MODEL 63 FIGURE 28: S PARAMETER COMPARISON OF CST AND ADS 64

FIGURE 29: ILLUSTRATION OF REFLECTION OF RIS 65 FIGURE 30: BEAM STEERING 69 FIGURE 31: BEAM STEERING USING GRAPHENE BASED RIS 70 FIGURE 32: BEAM STEERING @15-DEGREE WITH RIS 72 FIGURE 33: BEAM STEERING @15-DEGREE TOP VIEW WITH RIS 72 FIGURE 34: BEAM STEERING @30-DEGREE WITH RIS 73 FIGURE 35: BEAM STEERING @30-DEGREE TOP VIEW WITH RIS. 73 FIGURE 36: BEAM STEERING @60-DEGREE WITH RIS 74 FIGURE 37: BEAM STEERING @60-DEGREE TOP VIEW WITH RIS 74 FIGURE 38: GEAPHENE BASED RIS ANTENNA DESIGN 76 FIGURE 39: TERAHERTZ ANTENNA 78 FIGURE 40: S11 OF THZ ANTENNA 78 FIGURE 41: FARFIELD PATTERN OF UNIT CELL 80 FIGURE 42: RADIATION PATTERN OF THE QUAD PORT MIMO @ 2.85THz FOR ALL FOUR ELEMENTS 81 FIGURE 43: BEAM STEERING AT 3HZ WITH PORT 1 EXCITATION WITH ANTENNA 82 FIGURE 44: BEAM STEERING AT 3HZ WITH PORT 2 EXCITATION WITH ANTENNA 82 FIGURE 45: BEAM STEERING AT 3HZ WITH PORT 3 EXCITATION WITH ANTENNA 83 FIGURE 46: BEAM STEERING AT 3HZ WITH PORT 4 EXCITATION WITH ANTENNA 83 FIGURE 47: BEAM STEERING WITH NO PORT EXCITED WITHOUT ANTENNA 83

ABSTRACT Recent research endeavors have been dedicated to innovative wireless hardware designs and connection concepts aimed at fulfilling the ambitious objectives of 6th Generation (6G) wireless communications. The inclusion of Terahertz (THz) technology in modern infrastructure holds immense potential for shaping 6G networks, offering amplified throughput, extended coverage, heightened security, and improved positioning while reducing power consumption. The demand for efficient control over THz waves has grown alongside the advancements in wireless domain. RIS have garnered significant attention as a means of regulating electromagnetic waves. In this study, we investigate the utilization of a RIS employing graphene-based materials to control THz waves, with a specific focus on enhancing reflection performance and enabling beam steering. Our proposed RIS design entails an array of graphene based meta-atoms has been positioned over a ground which is made up of silicon substrate. The primary objective of this research is to achieve precise control over THz waves through the implementation of RIS and graphene-based materials, thereby optimizing reflection quality and attaining superior outcomes. Furthermore, we aim to direct THz waves to specific regions through beam steering techniques. Our aim is to achieve close to 100% reflection from 0.1 to 4 Terahertz, which is not been previously reported yet, while also enhancing gain. By leveraging the electrical reconfiguration capabilities of graphene-based meta-atoms through their chemical potential, we also strive to achieve 100% absorption within the graphene-based RIS. Moreover, by manipulating the unit cells and phase gradient of the structure, exceptional reflection performance is obtained. Our preliminary findings demonstrate the THz graphene-based RIS in facilitating efficient intelligent THz wireless communications. The proposed model offers a means of controlling THz waves with enhanced reflection and beam steering capabilities. Its implementation holds the potential for significantly improving system performance, increasing throughput, extending coverage, enhancing security, and refining positioning accuracy, all while reducing power consumption within 6G wireless communication networks.