Advanced mechanical and radiofrequency design of reflect array antennas for space applications

Abstract

The analysis, optimization, and design of advanced reflectarray (RA) antennas for space applications are investigated in this work. The study is focused on developing methodologies and tools able to be integrated into the industrial framework of this thesis. RA antennas are a relatively emerging technology in the space telecommunication framework, benefiting from the advantages of the conventional reflectors and array antennas for high gain applications. This work surveys the coupled mechanical and radiofrequency (RF) design aspects of RA antennas. The mechanical design of large RA antennas shows some limitations concerning the survivability in the harsh space environment. Indeed, strong thermoelastic deformations of the RA composite structures can remarkably affect the antenna’s electrical performances. This work surveys these aspects by proposing reliable and cost-effective structural solutions, which are consequently taken into account in the RA electrical design process. The electrical analysis and design process benefits from internal industrial tolls that are efficiently integrated with original tools developed in this thesis framework. The electrical design process lies in some hypotheses that allow an efficient design and op timization of the RA antenna layout, such as the local periodicity assumption. The local periodicity hypothesis is well respected in the RA design process investigated in this work by employing a particular unit cell, named Phoenix cell. The Phoenix cell geometries are efficiently handled in parametrized lookup tables to prevent any sharp geometrical transition on the RA layout. This work proposes and compares different design and optimization approaches in which the unit cells definition, and the subsequent lookup table construction, are efficiently integrated. The classical phase-only synthesis is surveyed and implemented. It represents the departing point for the direct layout optimization, aiming to improve the RA performances by naturally preventing any sharp geometrical transition on the RA layout. The optimization is conducted through a continuous and regular modulation of the RA cells geometries distribution by targeting prescribed performances, either on the aperture or the far-field. The coupled RF/mechanical design is applied to a concrete case of a large deployable RA for telecommunication spacecraft. Moreover, the electrical analysis and design of a small satellite RA antenna for payload data handling and transmission are investigated and implemented.