Terahertz focusing reflectarray with enhanced bandwidth

Abstract

This paper presents a planar terahertz reflectarray that employs stub-loaded square patches on a grounded substrate for efficient beam focusing at 1 THz. The proposed patch element can achieve a nearly linear and smooth phase response at the operating frequency through variation of its stub length. This feature is of great importance to the bandwidth performance of a reflectarray made of such elements. By the principle of reciprocity, the designed focusing device can also function as a collimator. The numerical results confirm the focusing capability of the designed reflectarray with a 3-dB bandwidth of 0.23 THz at 1 THz. This design can achieve over twice the operation bandwidth compared with existing designs.