The "Myth" of the Minimum SAR Antenna Area Constraint
A design constraint traceable to the early days of spaceborne Synthetic Aperture Radar (SAR) is known as teh minimum antenna area constraint for SAR.
SAR↗
Engineering topics
Johnson, W. T. K.
Publications and source records attributed to Johnson, W. T. K..
The "Myth" of the Minimum SAR Antenna Area Constraint
A design constraint traceable to the early days of spaceborne Synthetic Aperture Radar (SAR) is known as the minimum antenna area constraint for SAR. It specifies, as the name suggests, a minimum area for SAR antennas, to optimize performance.
design↗
The "Myth" of the Minimum SAR Antenna Area Constraint
A design constraint traceable ot the early days of spaceborne Synthetic Aperture Radar (SAR) is known as the minimum antenna area constraint for SAR. In this paper, it is confirmed that this constraint strictly applies only to the case where both the best possible resolution and the widest possible swath are the design goals. SAR antennas with area smaller than the constraint allows are shown to be possible, have been used on spaceborne SAR missions in the past, and should permit further, lower-cost SAR mission in the future.
Freeman, A.↗
Cassini Radar EQM Model: Instrument Description and Performance Status
The spaeccraft of the Cassini Mission is planned to be launched towards Saturn in October 1997. The mission is designed to study the physical structure and chemical composition of Titan. The results of the tests performed on the Cassini radar engineering qualification model (EQM) are summarized. The approach followed in the verification and evaluation of the performance of the radio frequency subsystem EQM is presented. The results show that the instrument satisfies the relevant mission requirements.
Borgarelli, L.↗
Cassini radar: Instrument description and performance status
The spacecraft of the Cassini mission is planned to be launched towards Saturn in October 1997. The mission is designed to study the physical structure and chemical composition of Titan. The results of the tests performed on the Cassini radar engineering qualification model (EQM) are summarized. The approach followed in the verification and evaluation of the performance of the radio frequency subsystem EQM is presented. The results show that the instrument satisfies the most relevant mission requirements.
Johnson, W. T. K.↗
Development Status of the Cassini Radar for Remote Sensing of Titan
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Cassini Mission to Planet Saturn surface imaging C↗
The Magellan Venus radar mapping mission
The NASA Magellan Venus Radar Mapper spacecraft, which will be placed into orbit around Venus on August 10, 1990, is described and its mission is discussed. The orbiter's 12-cm wavelength, multimode radar system is examined and the applications of its modes are addressed. In the SAR mode, it can image most of the Venus surface at a resolution of better than 300 m, approaching 120 m over more than half the planet. In the altimeter mode, the radar will determine topographic relief to a vertical accuracy of better than 50 m averaged over a surface resolution cell approximately 10 km in diameter. In the radiometer mode, the radar receiver can determine the surface radio emission brightness temperature with an absolute accuracy of 20 K, at a resolution of 2 K. The nature of the data products and the archiving plans are also considered.
Saunders, R. S.↗
Magellan radar system design
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Johnson, W. T. K.↗
Ambiguities in spaceborne synthetic aperture radar systems
An examination of aspects of spaceborne SAR time delay and Doppler ambiguities has led to the formulation of an accurate method for the evaluation of the ratio of ambiguity intensities to that of the signal, which has been applied to the nominal SAR system on Seasat. After discussing the variation of this ratio as a function of orbital latitude and attitude control error, it is shown that the detailed range migration-azimuth phase history of an ambiguity is different from that of a signal, so that the images of ambiguities are dispersed. Seasat SAR dispersed images are presented, and their dispersions are eliminated through an adjustment of the processing parameters. A method is also presented which uses a set of multiple pulse repetition sequences to determine the Doppler centroid frequency absolute values for SARs with high carrier frequencies and poor attitude measurements.
Li, F. K.↗