Shape Reconstruction of Concave Objects Based on High-Order Boundary Scattering Transform for Millimeter-Wave Near-Field Imaging

Millimeter-wave near-field imaging provides a promising solution for potential sensing applications. Although in many cases only the shape of the object is required, the conventional method often carries out a full image reconstruction of the target, thus suffers from slow imaging speed and high computational complexity. Moreover, conventional imaging results exhibit severe artifacts when facing complex concave targets due to high-order scattering. Both problems pose a significant obstacle for achieving sufficient accuracy in target recognition. To address these issues, this paper proposes a new shape reconstruction technique for millimeter-wave imaging of complex concave objects based on a high-order boundary scattering transform (HBST). Target contours are directly obtained by establishing a transform formula between the received wavefront under multiple reflections and the target boundaries. Multiple reflections propagation omitted in conventional imaging are fully included in the derivation of the HBST. Numerical simulations and experimental results are presented to verify the applicability and effectiveness of the proposed technique for dihedral-like structures.