Single layer reflectarray employing circular ring with open-circuited stub as phasing element

The paper presents the design of a linearly polarized single-layer reflectarray which employs a fixed-size circular ring with a variable-length open-circuited stub run around it as a phasing element. To achieve a slow phase slope, a thick foam material is used to support this element developed on a thin substrate. Investigations are performed to achieve a linear reflection phase as function of the stub's length. This goal is achieved by a suitable choice of the ring's radius and width and the stub's width. The phasing element offering best linear phase characteristics is used to design an X-band 13 × 13 element reflectarray. The full-wave simulation performed using CST Microwave Studio shows an increased 1dB gain drop bandwidth of the designed array antenna.