NASA - National Aeronautics and Space Administration

As part of the overall NASA earth science technology research effort, a half-size prototype model of light-weight, dualfrequency and wide-swath scanning antenna for the next generation of spaceborne precipitation radar has recently been developed. It operates radar channels at both 13.6 and 35 GHz for improved rainfall retrieval accuracy. The antenna for proposed spaceborne precipitation radar is an offset parabolic cylindrical reflector fed by two linear arrays. This design is adopted, instead of a doublecurved offset reflector, because it provides the required wide scan angle in the cross-track plane at both the Ku and Ka band operating frequencies. To demonstrate the technological readiness of the concept, the focus is on a half-scale model of 2.65 m operating at Ku and Ka band. In this paper, the technology development status on this Advanced Precipitation Radar Antenna will be presented. Design and characterization of the 2.65 m antenna is detailed by presenting the features of various components of the antenna, including simulation of the performance, 2 166 Ku and 4 166 Ka element feed array designs and evaluation and the design concept of the membrane reflector. Measurement results of the entire antenna system using a compact range facility will also be summarized.