A paper describes a frequency-scaled SweepSAR demonstration that operates at Ka-Band (35.6 GHz), and closely approximates the DESDynl mission antenna geometry, scaled by 28. The concept relies on the SweepSAR measurement technique. An array of digital receivers captures waveforms from a multiplicity of elements. These are combined using digital beamforming in elevation and SAR processing to produce imagery.
Ka-band (35.6 GHz) airborne SweepSAR using array-fed reflector and digital beamforming features eight simultaneous receive beams generated by 40-cm offsetfed reflector and eight-element active array feed, eight digital receiver channels with all raw data recorded and later used for beamforming. Illumination of the swath is accomplished using a slotted-waveguide antenna radiating 250 W peak power. This experiment has been used to demonstrate digital beamforming SweepSAR systems.
This work was done by Gregory A. Sadowy, Chung-Lun Chuang, Hirad Ghaemi, Brandon A. Heavey, Lung-Sheng S. Lin, and Momin Quddus of Caltech for NASA’s Jet Propulsion Laboratory. NPO-48376
This Brief includes a Technical Support Package (TSP).
Ka-band Digitally Beamformed Airborne Radar Using SweepSAR Technique
(reference NPO-48376) is currently available for download from the TSP library.
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Overview
The document is a Technical Support Package for the Ka-band Digitally Beamformed Airborne Radar using the SweepSAR technique, referenced as NPO-43876 in NASA Tech Briefs. It is part of NASA's Commercial Technology Program, aimed at disseminating aerospace-related developments with broader technological, scientific, or commercial implications.
The document outlines the objectives and findings related to the proposed DESDynI (Deformation, Ecosystem Structure, and Dynamics of Ice) mission, which focuses on advanced radar technology for Earth observation. It includes an overview of the SweepSAR system, detailing its design, performance, and operational capabilities. The SweepSAR technique is notable for its ability to generate high-resolution imagery and gather data on various environmental and geological features.
Key highlights include the performance of the radar's eight receive channels, where it was noted that Channel 8 exhibits lower power relative to others by 3-5 dB, and Channel 4 shows a distorted spectrum, which poses challenges for beam forming despite still being able to produce imagery. The document emphasizes the importance of these channels in achieving effective radar performance and the implications for data accuracy.
Additionally, the document discusses the hardware overview and test flight results from an airborne demonstration of the SweepSAR system. It provides insights into the reflector and feed configuration, modeling, gain patterns, and the impact of pointing and blockage on radar performance.
The document also includes a section on freeway imagery, showcasing a maximum power beam mosaic of a section of the 14 freeway, illustrating the practical applications of the technology in real-world scenarios.
Overall, the Technical Support Package serves as a comprehensive resource for understanding the advancements in radar technology through the SweepSAR technique, its applications in Earth observation, and the ongoing efforts by NASA to leverage these innovations for scientific and commercial purposes. For further inquiries or assistance, contact information for the Innovative Technology Assets Management at JPL is provided, emphasizing NASA's commitment to collaboration and technology transfer.
