M.M. Krutov1, T.A. Mirtalibov2, A.O. Slavyanskiy3, M.V. Fesenko4

1,3,4 JSC “Central radio-research institute named after academician A.I. Berg” (Moscow, Russia)

2 JSC “Almaz–Antey” Air and Space Defence Corporation” (Moscow, Russia)

The paper considers the issues of creating an onboard radar with a synthesized aperture, which is located on board a spacecraft and is designed for radar survey of the Earth's surface in data accumulation modes with subsequent transmission of this data to ground data reception and processing points on board the spacecraft in order to detect specified objects and transmit their coordinates to Earth.

In the course of the work, geometric calculations of the viewing modes of the Earth's surface were carried out to substantiate the requirements for the directional pattern of the active phased array antenna and the control of the main beam. Special software was used to calculate the radiation pattern of the active phased array antenna array, which takes into account the radiation patterns of the modules, the spatial structure of their location, as well as the amplitude-phase parameters of each module.

The simulation of the operation of an active phased array antenna array was also carried out in order to confirm the requirements for scanning sectors in conditions of a limited number of channels and finite discreteness of controlled phase shifters.

To aim the radar at the shooting object, it is necessary to measure the current coordinates of the spacecraft, the orientation of the spacecraft axes in the viewing space, as well as control the radar parameters (repetition rate, position of the time reception gates) and control the antenna diagram by the angle of the place and azimuth. The necessary control parameters are entered on the basis of ballistic calculations of the spacecraft movement, data from current trajectory measurements, and parameters of the geoid model.

Based on the results of the evaluation of the influence of spacecraft instability on the synthesis of radar images, the requirements for parameters, accuracy characteristics and efficiency of obtaining the current parameters of the spacecraft position and, accordingly, the antenna web to compensate for spacecraft deviations (due to insufficient stabilization) by electronically retargeting the beam of the active phased array antenna. Compensation of the beam deflection in the direction opposite to its displacement due to the instability of the spacecraft position can be carried out in an active phased array antenna array by changing the array of phase values in the receiving and transmitting modules.

The possibility of compensating for deviations and thereby preserving the quality of the radio hologram for constructing images in route and survey shooting modes is shown. To compensate for the violation of the position of any ray from their entire totality, it is necessary to be able to form a complete "belt" of additional rays around their "standard" group. Confirmation of the quality of the radio hologram in a detailed mode with the achievement of a high spatial resolution meter requires additional study.

Krutov M.M., Mirtalibov T.A., Slavyanskiy A.O., Fesenko M.V. Evaluation of the effect of instability of the spacecraft position on the synthesis of radar images. Radiotekhnika. 2022. V. 86. № 5. P. 55−63. DOI: https://doi.org/10.18127/j00338486-202205-07 (In Russian)

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