Modelling of THz Band Graphene Based Reconfigurable Intelligent Surfaces with High Directivity

Terahertz (THz) communication, which can provide a significant benefit to the developing communication technologies today, comes along with many problems. The most important of these problems are the high path loss and the direct line of sight (LOS) requirement in most of the communication schemes. Reconfigurable intelligent surface (RIS) designs, which can be brought as a solution to the line of sight requirement have been proposed in this research. The unit cells forming these surfaces cannot be designed using metal materials due to the characteristics of electromagnetic waves with THz frequency. Graphene material, according to its controllable surface impedance properties, provides both sufficient reflection conditions and can be used to create units with different reflective phase values with varying impedance values to create the RIS structure. In this study, a certain reflection phase range was obtained on a designed RIS unit cell and RIS structures that can direct the incoming plane wave to various angles using this unit were designed and simulated in CST Microwave Studio 2019 program.