Terahertz reflectarray antennas: An overview of the state-of-the-art technology

A reflectarray antenna combines the advantages of reflectors and phased-arrays. Due to its low profile, low loss, and versatile radiation properties, it has emerged as a new generation of high-gain antennas. Meanwhile, terahertz (THz) technology, which locates between microwave and infrared, is a frontier of the state-of-the-art electromagnetic research. Recently, the concept of reflectarray has been extended from microwave to THz and higher frequencies. In this paper, several available design methodologies on THz reflectarray antennas are reviewed, such as printed reflectarray antenna using traditional square patch, dielectric THz reflectarray antenna, and reflectarray antenna using graphene. Moreover, the concept and design methods about infrared reflectarray and optical reflectarray are also reviewed. It is expected that this overview will help to stimulate and promote creative THz reflectarray research in the near future.