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23 December 1997 Polarimetric multifrequency SAR measurements over sea at millimeter-wave frequencies
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For certain remote sensing applications millimeterwaves offer advantages over lower frequency radar bands and infrared systems. In comparison to the IR-region the most important advantages is the good all weather capability. With respect to the microwave radar bands mainly the coupling of millimeterwaves to small surface structures is significant. One very special item, typical for the use of millimeterwaves is the determination of signatures of the ocean surface where the small scale structures of the wave patterns of different origin give reason for its dynamic variation. To generate high resolution images the synthetic aperture approach is the favorite method also for the millimeterwave bands. These wavelengths allow some simplifications in the algorithms to be applied, namely the image distortions due to range migration and depth of focus can be neglected. The short aperture time which is reduced by the factor of the wavelength for an equal cross range resolution, leads to a much lesser influence of flight instabilities of the airborne platform, than have to be taken into account for classical microwave SAR. Additionally the image displacement of moving structures is less critical at millimeterwaves, as in SAR imaging this displacement is directly proportional to the aperture time. The polarimetric, high resolution experimental radar MEMPHIS (Millimeterwave Experimental Multifrequency Polarimetric High Resolution Imaging System) with simultaneous operating front-ends at 35 GHz and 94 GHz has been installed onboard a cargo aircraft in side-looking configuration. The paper describes the system configuration and the SAR processing algorithm and gives representative results for the generated radar images, compares the results at 35 and 94 GHz and illustrates techniques for signature enhancement by use of the polarimetry.
© (1997) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Stephan Boehmsdorff, Helmut Essen, and R. Makaruschka "Polarimetric multifrequency SAR measurements over sea at millimeter-wave frequencies", Proc. SPIE 3120, Wideband Interferometric Sensing and Imaging Polarimetry, (23 December 1997);

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