Single Layer Reflectarray With Circular Rings and Open-Circuited Stubs for Wideband Operation

The design of a single-layer reflectarray, which employs a new phasing element in the form of a fixed-size circular ring and a variable-length open-circuited stub, is presented. The array is developed on a thin substrate supported by a thick foam material. Investigations are performed to obtain a linear reflection phase as a function of the stub´s length when the element operates in a unit cell. This goal is achieved by a suitable choice of the ring´s radius and width and the stub´s width. In order to validate the simulated element´s reflection phase behavior, a waveguide simulator is manufactured to perform experimental tests. The phasing element offering best linear phase characteristics is used to design an -band offset fed 13×13 element reflectarray pointing at 20° from the broadside direction. Full-wave simulations performed using CST Microwave Studio show desired radiation characteristics of the designed array antenna. The simulated performance is confirmed by experimental tests performed on the fabricated reflectarray prototype showing a 17.8% 3-dB gain drop bandwidth.