SYNTHESIS OF SURFACES COHERENT IMAGES BY SPATIALLY DISTRIBUTED MULTICHANNEL SYSTEMS IN THE FRAUNGOFER REGION

Abstract

The geometry of remote sensing problem in the far field Fraunhofer region is proposed and analytical expressions for the observed field in every point of the receiving area are obtained. The conception of primary images recovering is proposed. It is based on application of the integral transformation with the kernel of inverse Fourier transform. It is shown that the primary coherent images are sliding short-scale Fourier transformation of the ideal surface images. This result corresponds to the classical theory of resonant scattering. The main mathematical operations of the received electromagnetic field processing in multichannel optical and radio engineering systems are developed. The resolution of the primary coherent images is analyzed and possible ways of its enhancement based on secondary multi-channel and multi-position signal processing and aperture synthesis method are shown. It is suggested to call images obtained after secondary processing the synthesized coherent images, and algorithmic or physical operations of such processing to call aperture synthesis. To restore synthesized coherent images it is proposed to apply inverse short-scale Fourier transformation to the primary coherent images. To study the possibilities synthesized coherent images recovering, several geometries for surface remote sensing are proposed in the Fraunhofer region. Observation methods in accordance with these geometries are called the fan mode, serial mode and spotlight mode. Several algorithmic operations for recovering synthesized images were developed according to these modes. Studies of the obtained results show that in the far-field Fraunhofer region it is possible to perform aperture synthesis and to increase the spatial resolution only in the case of spotlight mode.