- Synthetically thinned aperture radar
Synthetic Thinned Aperture Radiometry (STAR) is a method of radar in which the coherent product (correlation) of the signal from pairs of antennas is measured at different antenna-pair spacings (baselines) [Synthetic Thinned Aperture Radiometry (STAR) Technologies Enabling 10-km Soil Moisture Remote Sensing from Space, J.R. Piepmeier , F.A. Pellerano, Proc. NASA Earth Science Technology Conference, (College Park, MD), 2002. [http://esto.nasa.gov/conferences/estc-2002/Papers/B2P7(Piepmeier).pdf] ] . These products yield sample points in the Fourier transform of the brightness temperature map of the scene, and the scene itself is reconstructed by inverting the sampled transform [D. M. Le Vine, Synthetic aperture radiometer systems, IEEE Trans. Geosci. Remote Sensing, vol. 37, no. 12, pp. 22282236, 1999.] . The reconstructed image includes all of the pixels in the entire field-of-view of theantennas.
The main advantage of the STAR architecture is that it requiresno mechanical scanning of an antenna. Using a static antenna simplifies the antenna system dynamics and improves the time-bandwidth product of the radiometer. Furthermore, aperture thinning reduces the overall volume and mass of the antenna system. A disadvantage is the reduction of radiometric sensitivity (or increase in rms noise) of the image due to a decrease in signal-to-noise for each measurement compared to a filled aperture. Pixel averaging is required for good radiometric sensitivity.
Synthetic aperture radar
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