Wideband Reflectarrays with Improved Performances for Space Applications

Abstract

This work presents the design and optimization of two very large reflectarrays with improved polarization purity for Direct Broadcast Satellite missions in dual-linear polarization. The first antenna is a one-meter contoured-beam reflectarray working in a 15% frequency band providing European coverage. The second reflectarray has a diameter of 1.1 meters and provides coverage for South America in transmit and receive bands. In both cases, the design approach is as follows. First, a layout is obtained at central frequency. Then, using a limited number of degrees of freedom (DoF), a copolar only optimization is carried out in the whole frequency band. Finally, increasing the number of DoF, cross-polarization requirements are also included in the optimization. For the reflectarray with European coverage, a minimum copolar gain of 28dBi is obtained inn the whole band, with XPI values higher than 31.5dB. On the other hand, the reflectarray with South American coverage complies with all copolar and cross-polarization requirements with a loss budget of at least 0.49 dB in both receive and transmit bands.