A Reflectarray With Small Focal Diameter Ratio

In this paper, a novel method to design a reflectarray antenna with a small focal diameter ratio (F/D) is proposed. In the traditional designing approach, the reflecting phase of the element in the reflecting surface is achieved by placing the element in the periodic boundary. However, in this paper, the reflecting phase is obtained by a 7×7 array illuminated by the plane waves. For the reflectarray with a small focal diameter ratio, the gain can be improved by the proposed method compared with the traditional method. To verify the method, two 16×16 reflectarrays designed by the traditional and proposed methods are simulated, respectively. In the working band from 9.6 GHz to 10.8 GHz, the gain of the reflectarray is improved by 1.39 dB at most. And the first sidelobe level (SLL1) of the reflectarray is less than -10 dB in the operating band.