Spaceborne bistatic FMCW SAR imaging method based on FS algorithm

Abstract

Frequency modulated continuous wave synthetic aperture radar (FMCW SAR) is a new radar system, which has a series of advantages such as small volume, light weight, high resolution, low power consumption and low interception. At present, FMCW system is widely adopted in small or micro SAR. FMCW SAR transmits signals in the whole sweep period (PRT), and the duty cycle of the signal is more than 80%. Ignoring the instantaneous range change of the target caused by the continuous movement of the radar platform in the process of transmitting the signal will lead to the distortion of the received echo signal. In order to improve the antenna isolation and enhance the application of the algorithm in practical engineering, this paper adopts the same orbit forward dual satellite mode with the space of 10km and the side view of the transmitting satellite, and models the echo signal of FMCW SAR under the dual satellite system, The signal characteristics are analyzed. This paper explains that the continuous motion of the dual satellite platform produces a Doppler frequency shift in the range direction. Firstly, frequency scaling is performed in the azimuth frequency domain, and then the residual video phase (RVP) compensation is completed in the two-dimensional frequency domain. An improved frequency scaling (FS) algorithm suitable for dual satellite FMCW SAR imaging processing is given, The correctness and feasibility of echo model and imaging algorithm are verified by point target simulation.