![]() SAR Workhorse (global mapping change detection monitoring of areas with low to moderate penetration higher coherence) ice, ocean maritime navigation High resolution SAR (urban monitoring, ice and snow, little penetration into vegetation cover fast coherence decay in vegetated areas) ![]() Rarely used for SAR (satellite altimetry) Rarely used for SAR (airport surveillance) The table below notes the band with associated frequency, wavelength, and the application typical for that band. The different wavelengths of SAR are often referred to as bands, with letter designations such as X, C, L, and P. Radar sensors utilize longer wavelengths at the centimeter to meter scale, which gives it special properties, such as the ability to see through clouds (view electromagnetic spectrum to the right). Optical sensors such as Landsat's Operational Land Imager (OLI) and Sentinel-2's Multispectral Instrument (MSI) collect data in the visible, near-infrared, and short-wave infrared portions of the electromagnetic spectrum. In this concept, a sequence of acquisitions from a shorter antenna are combined to simulate a much larger antenna, thus providing higher resolution data (view geometry figure to the right). Hence, scientists and engineers have come up with a clever workaround - the synthetic aperture. (That's over 47 football fields!)Īn antenna of that size is not practical for a satellite sensor in space. From a satellite in space operating at a wavelength of about 5 cm (C-band radar), in order to get a spatial resolution of 10 m, you would need a radar antenna about 4,250 m long. For a given wavelength, the longer the antenna, the higher the spatial resolution. The spatial resolution of radar data is directly related to the ratio of the sensor wavelength to the length of the sensor's antenna. The electromagnetic spectrum with microwave bands inset.
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