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.