A.S. Petrov

Lavochkin Association (Khimki, Moscow region, Russia)

Space systems for remote sensing of the Earth (remote sensing), implemented on the basis of synthetic aperture radars (SAR), are usually installed at platforms flying in low orbits of 500…1000 km. These systems use almost the entire spectrum of electromagnetic waves, namely, the P-, L-, S-, C- and X-bands of the microwave. The reason is that in these five main ranges, the physics of the interaction of waves with the atmosphere and with objects on the Earth's surface differs significantly, and also that there are fundamental features in the schematic-constructive (and, therefore, mass-dimensional) implementation of antenna systems that will have to be placed on a space platform.

To date, several modes of SAR operation have been proposed and used in practice: route, or side view; detailed or telescopic; survey (with several bands of capturing the Earth's surface, including with rapid return scanning – progressive scan); bi- and multistatic; interferometric (with its two different basic options for selecting moving targets and forming digital maps of surface elevations); tomographic; finally, holographic [4–9]. At the same time, the starting point for analyzing the characteristics and determining the appearance of the equipment continues to be the earliest in time of its appearance, the basic side-view mode [10–12].

Obviously, the existence of various options for the implementation of space SAR is acceptable, each of which has its own technical appearance. Choosing from an acceptable set of parameters of the locator that determines its appearance, a specific (recognized by the developer as optimal) combination of them turns out to be a difficult multiparametric and multi-criteria task. Its solution can be approached along various trajectories in binary (parameters/characteristics) and multidimensional (with at least dozens of elements for each of these two interdependent components) space.

In the article [13], a technique for analyzing the characteristics of a space radar at given values of parameters that determine its appearance has been developed. However, the initial task, nevertheless, is to first identify these parameters for any frequency range.

The paper presents the relationship between the size of the antenna aperture and the swath of the Earth's surface when using a spherical Earth model and shows its graphical dependencies. The limitations imposed on the size of the aperture of the antenna of the space locator by its geometric resolution in the longitudinal direction and the equation of the energy potential are revealed. The minimum permissible vertical size of the antenna aperture and the maximum permissible angular width of the Earth's surface capture band at a given azimuthal resolution are determined. The approach to the choice of the aperture size of the radar antenna is revealed, in which the limitations on the energy potential of the system and on the pulse time characteristics are simultaneously satisfied, a closed method for determining the basic parameters of the locator is developed and its verification is made. With the help of this technique, calculation tasks of the basic parameters of space RSA installed on low-flying platforms and operating in three X-, L- and P-wave bands are being solved.

Petrov A.S. Appearance formation of the Earth remote sensing low-orbit space systems. Achievements of modern radioelectronics. 2022. V. 76. № 5. P. 26–41. DOI: https://doi.org/10.18127/j20700784-202205-02 [in Russian]

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