A.S. Petrov1

1 Lavochkin Association (Khimki, Moscow region, Russia)

In traditional SAR systems implemented using analog equipment, the longitudinal component of the geometric resolution is directly proportional to the transverse width of the capture of the Earth's surface by the antenna pattern. Therefore, the greater the width of the capture band, the worse will, generally speaking, inevitably become the geometric resolution of the equipment. With high resolution and a narrow capture band, system performance decreases. The solution to the problem is achieved by using digital beamforming methods, which allow implementing new modes of the SAR operation, as well as special algorithms for processing large volumes of incoming information.

A brief overview of the recent years achievements in the field of SAR with digital beamforming is presented, with the help of which it is possible to overcome the limitation imposed on high resolution in a wide capture band inherent in traditional systems implemented according to analog ideology. The calculated ratios and graphical dependences of the length and width of the space radar antenna on the angle of sight of the center of the Earth's surface capture band are given at: six values of its width (from 25 to 800 km) at three values of the pulse ratio and in three wavelength ranges X, L and P, at low orbit flight altitude of the spacecraft. An analytical review of the SAR construction principles is made, in which the principle of digital beamforming is implemented using: a longitudinal subaperture structure, angular scanning of the AP beam when receiving an echo signal, multidimensional coding, a reflector irradiated by an antenna array. A comparison of the parameters of modern and promising space SAR is given.

In terms of performance, new systems can surpass previous generations by several orders of magnitude. At the same time, to achieve this result, you have to pay a serious price. Firstly, the volume of the digital data stream, simultaneously generated by not one, but many sub-apertures, increases many times; secondly, the requirements for frequency and phase synchronization of the equipment of the array fragments are tightened; thirdly, the algorithms of signal processing and image formation are repeatedly complicated.

Petrov A.S. Realization principles review of new foreign space remote sensing systems with high resolution in a wide swath. Achievements of modern radioelectronics. 2023. V. 77. № 2. P. 44–57. DOI: https://doi.org/10.18127/j20700784-202302-04 [in Russian]

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