Reconfigurable Reflectarray and Transmitarray Antennas for Radar Applications in Space

Kurzfassung

Earth observation imaging radar satellites, such as Synthetic Aperture Radar (SAR), play an important role in many areas, such as monitoring climate change or assisting in the event of natural disasters. A key element of the radar setup is the antenna, as it directly affects the inherent properties of the SAR image, such as footprint, resolution, SNR or polarimetric characteristics. Typically, SAR satellites such as TerraSAR-X and Radarsat-2 use active phased arrays consisting of slotted waveguide or patch antennas. However, these state-of-the-art solutions have significant drawbacks: they often rely on complex feed networks, resulting in high losses. In literature, Digital Beam Forming (DBF) antennas are proposed as a solution, offering greater flexibility in data processing and beam steering. However, they require a large number of channels, which also means a large amount of data. Considering the recent developments and technological advances of reconfigurable reflectarray and transmitarray antennas in the field of communications, they could be a suitable candidate for future SAR satellites. Promising advantages such as highly flexible beam steering and high antenna efficiency can be provided. However, wide bandwidth (>10%) and dual polarization still seem to be a challenging task. The talk discusses the basic operation principle of reflectarray and transmitarray antennas and presents two innovative approaches for application on SAR satellites. Namely, a transmitarray fed by a leaky wave antenna in the near-field, which allows an ultra-flat design with less losses, and a space-deployable reflectarray consisting of tensioned Kapton foils.