Contoured-Beam Dual-Band Dual-Linear Polarized Reflectarray Design Using a Multiobjective Multistage Optimization

This communication presents a dual-band design procedure applied to a very large contoured-beam reflectarray with improved copolar and cross-polarization performances for direct broadcast satellite (DBS) in dual-band dual-linear polarization. The reflectarray is elliptical, with the axes of 1.10 and 1.08 m, and provides coverage for South America in transmit (11.70-12.20 GHz) and receive (13.75-14.25 GHz) bands. The novel dual-band design approach is based on the use of a multiresonant unit cell with several degrees of freedom (DoFs). It is divided into several stages to facilitate convergence toward a broadband high-performance reflectarray. First, a narrowband layout is obtained at the central frequency with a phase-only synthesis. Then, using a limited number of DoFs, a copolar-only optimization is carried out in both frequency bands maximizing the copolar figure of merit. Finally, increasing the number of DoFs, cross-polarization requirements are also included in the optimization procedure. The optimized antenna complies with all copolar and cross-polarization requirements with a loss budget of at least 0.62 dB in both receive and transmit bands, outperforming earlier works in the literature while using a smaller antenna than previously proposed for this mission.