Contoured-Beam Dual-Band Dual-Linear Polarized Reflectarray Design Using a Multi-Objective Multi-Stage Optimization

Abstract

This work 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 in dual-band dual-linear polarization. The reflectarray is elliptical, with axes of 1.10 and 1.08 meters, and provides coverage for South America in transmit (11.70 GHz–12.20 GHz) and receive (13.75 GHz–14.25 GHz) bands. The novel dual-band design approach is based on the use of a multi-resonant unit cell with several degrees of freedom (DoF). It is divided in several stages to facilitate convergence towards a broadband high-performance reflectarray. First, a narrowband layout is obtained at 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 DoF, 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.