Abstract:

The existing inverse synthetic aperture radar (ISAR) imaging methods for uniformly accelerative rotating targets usually estimate the rotation parameters via 2-D search, which leads to a huge computational load. A novel ISAR imaging method based on chirp-Fourier transform is proposed, which utilizes the characteristic of uniformly accelerative rotating target’s echo phase that the ratio of the coefficient of the second order term of scattering point’s echo phase to that of the first order term is only determined by target’s rotation parameters. The estimate of the ratio can be obtained by searching the frequency modulation coefficient of chirp-Fourier transform that minimizes the entropy of target’s cross-range profile, which is a 1-D search. Then the well-focused ISAR image can be obtained by taking corresponding chirp-Fourier transform on each range cell’s echo. Simulation results verify the validity of this method.