ON THE FOCUSING OF THE OCEAN SWELL IMAGES PRODUCED BY A REGULAR AND BY AN INTERFEROMETRIC SAR

Focusing of a monochromatic ocean wave image by either a regular or an interferomeric SAR (INSAR) is studied. The model developed simulates the images of both SAR and INSAR for an arbitrary focus setting. The e ffects of the various operational parameters, i.e., integration and sc ene coherence times, ocean wave length, direction and amplitude, etc., on the focus sensitivity of both SAR and INSAR is examined. A dimensi onless focusing parameter a which depends on the platform velocity and on the azimuthal component of the phase velocity of the imaged ocean wave is introduced. It is shown that a is the major parameter which de termines the image contrast of the regular SAR output, as well as that of the magnitude and the phase components of INSAR. The focus sensiti vity, however, is also a function of the imaged ocean wave parameters. The effects of the varying SAR integration time and of the scene cohe rence time on the contrast of the resulting image is also examined.