Accurate near-field millimeter-wave imaging of concave objects using multistatic array

This paper discusses near-field imaging of complex objects under multistatic array configurations. Due to high-order scattering from concave surfaces, severe artifacts are often encountered when imaging high-contrast complex targets, which makes it difficult for applications that require accurate near-field imaging and recognition. Furthermore, concave objects often exhibit strong scattering directivity, which requires complete multistatic measurements in order to deliver accurate surface reconstructions. In this paper, accurate imaging of concave objects using multistatic array is investigated. An analytical forward model for dihedral-type concave objects are formulated using shooting and bouncing rays (SBR) principle and further used to create a new reconstruction algorithm for accurate multistatic imaging. The mechanism of multiple reflections under multistatic configurations and the formation of artifacts are also analyzed. Numerical simulations and experimental results are presented to demonstrate the correctness of the proposed forward model and the performances of the proposed imaging algorithm.