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Effect of trajectory instabilities on the characteristics of synthetic aperture radar antenna due to the rotation of the phase center of the real antenna

DOI 10.18127/j20700814-201201-01


B. G. Tatarsky, D. A. Yasentsev

In the real work of radar systems with a synthetic aperture antenna (SAR) is one of the most important tasks is to compensate a phase distortion of the trajectory signal, leading to uncontrolled deviations of the trajectory of a real antenna phase center (PCA) from the line of the specified path (LSP) and reduce the quality of the formed radar images (RI). Phase distortion caused by tracking instability, the elastic vibrations. In other designs the carrier and SAR sensor error parameters of motion of the aircraft can reach tens or hundreds of degrees, which can lead to the impossibility of coherent signal accumulation, and, consequently, the inability to synthesize an artificial aperture antenna. When installing the antenna on the blade of a helicopter-type aircraft trajectory PCA will be determined by the law of motion rotor tip the carrier so it is important to consider the impact on synthetic aperture trajectory instabilities associated with the process of rotation of the blade. In considering it is believed that the helicopter center of mass (CM) is fixed, ie, the helicopter is hovering. Based on various descriptions of the rotation rotor blade (HB) heli-copter (in terms of aerodynamics and strength), it is shown that the major destabilizing factor, leading to the trajectory instability, are: flapping motion (flapping) of the blade in the vertical plane (the plane of the stroke) due to interaction with air flow: fluctuations in the blade plane of rotation; change the blade angle of attack; the natural oscillations of the blade as a rotating non-rigid elastic beam; vibration CM of helicopter, and, consequently, the rotor head, around which the rotation. We examined the influence of the above-mentioned destabilizing factors on the characteristics of SAR, based on a mathematical model developed by a trajectory signal processing system SAR. Model allowed us to obtain quantitative estimates of impact of phase distortion on the essential characteristics of SAR – the resolution of the azimuth, the dynamic range of the radar image is formed and the energy potential. Based on the work of analysis, it was concluded that, when placed on the helicopter blades PCA errors in the determination of PC in the process of synthesizing primarily are caused by vibration of the fuselage and the vibrations of the blade itself.


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