Comparison and analysis of point target reference spectrum of FMCW synthetic aperture imaging sensor

Abstract

Abstract Frequency-modulated continuous-wave (FMCW) synthetic aperture imaging sensor (SAIS) combines FMCW technology and SAIS techniques which makes a lightweight, high-resolution, and cost-effective imaging sensor. FMCW SAIS systems are going to play an important role in airborne and spaceborne earth observation fields. However, the stop-and-go approximation used in conventional pulsed SAIR (e.g., synthetic aperture radar—SAR) is no longer valid due to the long signal duration time or low wave propagation speed. To exploit the potentialities of an accurate signal model under FMCW SAIS circumstances, this article presents the relationship and remarkable differences between the analytical FMCW SAIS point target reference spectrum model and the traditional ones in pulsed SAR and Synthetic Aperture Acoustic imaging system, and validates the significance of the additional range–azimuth coupling term and range walk term in FMCW SAIS spectrum introduced by the variation of slant range during the long pulse durations, and highlight the limitations of other two spectra. Finally, the simulation experiments are carried out to compare the performance of the aforementioned spectrum formulations.