The SAR and scatterometer antennae on ERS-1

ERS-1 is the first remote sensing satellite of the European Space Agency. Its most important payload is the Active Microwave Instrument (AMI). The AMI is a combination of a synthetic aperture radar (SAR) and a synthetic aperture radar (SAR) and a scatterometer. The SAR antenna will be ten meters long and one meter wide and will be built in carbon fiber. The three scatterometer antennae with sizes of 3.6 by 0.38 meters and 2.3 by 0.38 meters, respectively, will be built out of aluminum. All four antennae are planar arrays of slotted waveguides. The critical areas are the high power the antennae have to handle, the extreme gain stabilities required, and the combination of high mechanical stiffness, tight thermal distortion tolerances, low mass, and small storage volume. The paper outlines the problems of the AMI antennae, the electrical and mechanical designs, and the expected performances.