A Two-Dimensional Scanning Antenna Based on Metamaterial Luneburg Lens in Terahertz Band

In this paper, a two-dimensional (2-D) scanning antenna based on a metamaterial Luneburg lens in the terahertz band is proposed. The design of the metamaterial Luneburg lens hinges on the extraction of equivalent electrical parameters from one-dimensional homogeneous metamaterials. Through full wave simulation, the reflection and transmission coefficients of the metamaterial units allow for the retrieval of their equivalent impedance and equivalent refractive index. The electrical parameters of the metamaterial unit are determined by the radius of the circular holes etched on the metal layer of the dielectric slab. This isotropic unit enhances the versatility in the application of the Luneburg lens. The phase scanning capacity of this metamaterial Luneburg lens is combined with the frequency scanning capacity of the leaky wave antenna to achieve the 2-D scanning function. The leaky wave antenna uses an inverted microstrip line as the transmission line, thus avoiding the challenge of fabricating metal vias in the terahertz band. The peak gain of this Luneburg lens antenna, obtained from simulation, reaches 17.9 dBi. Additionally, the phase scan can cover the elevation range from -26° to 26° while the frequency scan can cover the elevation range from -10° to 10°. It is anticipated that this 2-D scanning antenna in the terahertz band will find certain applications in 6G communications.