A Broadband Planar Reflectarray Antenna Employing Tightly Coupled Slot Elements

A novel broadband planar reflectarray antenna is proposed. The reflectarray element consists of a rectangular patch embedded with a pair of symmetrical inverted L-shaped slots, and the phase shift of the element is achieved by adjusting the length of the slots. The array bandwidth is significantly extended by introducing the tightly coupled effect through connecting adjacent elements. Based on the proposed elements, a square aperture reflectarray antenna with 450 elements is designed. Simulation results demonstrate that the presented reflectarray antenna realizes a stable radiation pattern, low cross-polarization, reasonable gain and aperture efficiency in a wide frequency band from 3 to 6 GHz. The 1 dB and 1.5 dB gain bandwidth of 22.9% and 44.4%, respectively, are also obtained. With its broadband performance as well as single-layer aperture, the proposed reflectarray antenna is a promising candidate for various wireless applications.