A High-Order Extended Reconstruction Algorithm for Microwave Imaging of Coupled Arbitrarily Shaped Targets

In this study, we propose an approach for high-order scattered field imaging without requiring prior knowledge of target geometry. Subcoupling edges are extracted from the initial target contours, which are derived from the backprojection imaging of the first-order scattered field and subsequent morphological refinement. High-order scattering is hypothesized to stem from the interaction between the extracted subcoupling edges and the unaccounted-for coupling edges. To explore these interactions, rectangular subfocusing regions are defined to cover the probable positions of the missing edges. Leveraging these regions along with the extracted subcoupling edges, high-order propagation paths are determined. By formulating high-order propagation distance equations and implementing individual phase compensation for each high-order scattering component, we achieve accurate imaging of high-order scattered fields, offering a significant advancement in the relevant research domain. Both simulations and experiments demonstrate the effectiveness of the proposed method, achieving a 20% expansion in the visible region compared to first-order imaging in simulation scenarios.