Optimum design of dual band shaped-beam circularly polarized reflectarray antenna based on physical optic method

Abstract

A shaped-beam dual-band reflectarray (RA) with shared aperture is designed and simulated in this communication. Desired radiation patterns are considered squared cosecant and pencil beam in elevation and azimuth planes for both bands, respectively. This antenna has been designed to operate at X-Band (9.6–10.9 GHz) with left-hand circular polarization and K-Band (19.1–21.6 GHz) with right-hand circular polarization. A thin layer of Frequency Selective Surface is used as a band separator to reduce mutual coupling between two frequency bands. A cross dipole with variable arc-shape delay line, which has very low cross polarization, is used as the radiation element for both bands. The capability of operating in different polarizations is an advantage of the proposed element. To obtain shaped-beam pattern for both bands, an optimization method based on physical optic is adopted. In the synthesis method, far-field radiation patterns are evaluated as a function of the tangential electric field components on the reflecting surface. Lower and higher band RAs are implemented on 30 × 30 cm2 and 18 × 18 cm2 Rogers 4003 substrate, respectively. Finally, the whole structure is simulated with CST software and shows a good agreement between the simulation and the ideal patterns at two bands. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:690–702, 2016.