Aerospace Technic and Technology

The subject matter of the article is the method of synthesis of aperture for solving problems related to the restoration of images of a static scene. The goal is to develop a new method and substantiate its operability in one of the possible surface survey modes for remote sensing or non-destructive testing of objects. The tasks to be solved include substantiation of the method of static synthesis of aperture; to proposing a new method of view and opportunities to improve the accuracy of restoring the scene under study. The methods used are all the underlying assumptions and new definitions were obtained within the theory of diffraction, the Kirchhoff and Rayleigh-Sommerfeld theorems, and the Huygens-Fresnel principle. The following results were obtained. Using a phenomenological approach, the concept of a coherent image of a surface is defined, which is divided into three components: the scattered field in the observation area, primary and secondary processing of the scattered field. The main operations of restoring primary coherent images, the operations of focusing the antenna system on each point of the surface under study, and the possibility of increasing their spatial resolution in synthetic aperture radars are shown. The spread and basis functions are defined, which determine the resolution of the restoration of coherent images. The structure of the coherent image in the static synthesis of the aperture in the Fraunhofer zone is determined. The telescopic mode was chosen as the surface survey mode, assuming that the area is surveyed crosswise in two mutually perpendicular directions (multi-pass or multi-look modes). The resolution of the method of static synthesis of the aperture is studied when the surface is viewed along a trajectory in the form of a cross. For such a view, the primary and secondary synthesized images do not have the required resolution. It is proposed to solve this problem by finding cross terms with spread functions narrow in both coordinates, by forming signals proportional to the intensities of the total and difference coherent images and performing mathematical operations on them. Conclusions. The possibility of image formation by sparse antenna arrays is shown. Because of the study, it was proved that with a cross-shaped view, the image structure is the scattering cross-section of the surface under study.

statistical synthesis of aperture; remote sensing; mathematical method formalization; block diagram

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