An optimization-based design of a wideband, polarization-independent reflectarray antenna at terahertz frequencies

A broadband reflectarray antenna is proposed for operating at THz frequencies. An array of single-layer elements is composed of gold patches printed on a grounded cyclic olefin copolymer (COC) substrate. The elements are designed to have a smooth and linear phase reflection curve versus element positions. A random hill-climbing (RHC) optimization algorithm is applied to obtain the broadest bandwidth around the design frequency. The proposed antenna shows 3 dB relative bandwidth of 25% ranging from 0.9 to 1.15 THz, and it has a polarizationindependent feature and low loss for better reflectarray performance.