A. Yu. Larin1, S. E. Mishchenko2, P. N. Bashly3
1, 2 Federal State Unitary Enterprise “Rostov Scientific Research Institute of Radio Communications” (Rostov-on-Don, Russia)
3 Rostov branch of Russian Customs Academy (Rostov-on-Don, Russia)

2 mihome@yandex.ru, 3 bpn973@mail.ru

Airborne radar systems placed on airplanes and spacecraft are used to obtain high-quality radio images of the underlying surface and highlight moving targets against its background. In accordance with the antenna approach, when forming a radio image in synthetic aperture radars, they rely on known parameters of the trajectory of the platform. At the same time, the heterogeneity of the signal propagation medium, the instability of the amplitude-phase characteristics of the receiving and transmitting equipment, as well as deviations from a given trajectory lead to a decrease in the quality of radio images. The restoration of their quality is achieved through the use of autofocus algorithms. Well-known autofocus algorithms are based on reducing quadratic phase distortion by selecting the focusing range of the synthesized aperture, as well as by image processing in the area of bright point echoes. The paper considers a modification of the well-known Gershberg-Saxton algorithm, which was proposed to restore the phase front of the light field, but applied to the problem of autofocus of the synthesized aperture.

The purpose of the work is to improve the quality of radio images obtained using a synthetic aperture radar. To achieve this research goal, the following tasks need to be solved: 1) substantiating the Gershberg-Saxton algorithm in relation to the problem of autofocus in a synthetic aperture radar; 2) checking the algorithm's performance.

The modification of the Gershberg-Saxton algorithm for reconstructing the phase front of a wave received by a radar with a synthesized aperture has been justified. Unlike the well-known algorithm, the relationship between the input plane and the observation plane is based on a synthesized aperture model. In addition, new operations have been introduced during the initialization of the algorithm. Numerical studies have confirmed the algorithm's operability. When implemented, the noise level of the phase distribution is eliminated, and the noise level in the observation plane is reduced. At the same time, the distinctness of the two marks in the image is preserved.

Larin A.Yu., Mishchenko S.E., Bashly P.N. Synthetic aperture radar autofocus based on the Gershberg-Saxton algorithm. Antennas. 2025. № 2. P. 30–40. DOI: https://doi.org/10.18127/j03209601-202502-04 (in Russian)

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