Near-Field Millimeter-Wave Imaging via Arrays in the Shape of Polyline

This article proposes a polyline-shaped array-based system scheme, associated with mechanical scanning along the array’s perpendicular direction, i.e., the vertical direction, for near-field millimeter-wave (MMW) imaging. Each section of the polyline is a chord of a circle with equal length. The polyline array, which can be realized as a monostatic array or a multistatic one, is capable of providing more observation angles than the linear or planar arrays. Furthermore, we present the related 3-D imaging algorithms based on hybrid processing in the space domain and the spatial frequency domain. The nonuniform fast Fourier transform (NUFFT) is utilized to improve the computational efficiency. The proposed algorithm runs even faster than the wavenumber domain algorithms for linear or circular-arc multiple-input–multiple-output (MIMO) arrays. This is due to the fact that the latter needs higher dimensional processing that requires more memory usage and time. Numerical simulations and experimental results are provided to demonstrate the efficacy of the proposed technique in comparison with the most commonly used arrays and algorithms.