Image reconstruction algorithm based on frequency-wavenumber decoupling for three-dimensional MIMO-SAR imaging

Abstract

In this paper, a frequency-wavenumber decoupling algorithm with high-efficiency and high-precise for three-dimensional (3-D) multiple-input-multiple-output synthetic aperture radar (MIMO-SAR) imaging is proposed. Based on one-dimensional (1-D) MIMO array combined with synthetic aperture scan along another dimension, MIMO-SAR imaging scheme allows the number of array elements to be greatly reduced compared with the two-dimensional (2-D) MIMO arrays. By multi-dimensional Fourier transforming and Method of Stationary Phase (MSP), analytical expression of the object function in the frequency-wavenumber domain was derived. By further expanding the range Fourier transform factor to its Taylor series form, the range compression can be realized by a simple fast Fourier transform (FFT) without multi-dimensional interpolation. After that, a decoupling factor was multiplied to compensate for the cross-range and range coupling in frequency domain. Finally, 2-D IFFT is carried out after rearrangement in the MIMO spatial frequency to get a fully focused 3-D image. Simulation and experimental results demonstrated that the algorithm can obtain the same high-precision images as back projection (BP) algorithm, and has the same high efficiency as range migration algorithm (RMA) while avoiding cumbersome multi-dimensional interpolation. A bistatic prototype imaging system in 0.1 THz band was designed for the proof-of-principle experiments. The 3-D reconstruction results of different targets were presented to verify the theoretical results and effectiveness of the proposed algorithm for MIMO-SAR imaging.

Phase Shift Migration with Modified Coherent Factor Algorithm for MIMO-SAR 3D Imaging in THz Band

“…To find out the relationship between the bistatic data and the 'exploding fields', 3D FT is firstly performed on (5) over x t , x r and y to obtain the spatial wavenumber spectrum [24].…”

“…This non-interpolation approach avoids the truncation effect of the interpolation kernel. Although the calculation efficiency of the PSM algorithm is slightly slower than that of RMA using nearest neighbor interpolation, the PSM algorithm can achieve higher imaging quality and is more suitable for short-range high-precision imaging applications [24]. In addition, some virtual monostatic array methods have also been reported in the MIMO-SAR scheme [25], which can avoid the data rearrangement operation to increase the computational efficiency.…”

A Millimeter-Wave 3D Imaging Algorithm for MIMO Synthetic Aperture Radar

“…Although the accumulation operation will affect the imaging efficiency, the results will be more accurate. In addition, there are also image reconstruction algorithms based on frequency-wavenumber decoupling for MIMO-SAR [12,19]. The same reasonable phase transformation is used instead of interpolation to make the imaging results more accurate.…”