Microwave tomography: From theory to practical imaging systems

Abstract This paper deals with numerical processing techniques and practical applications of active microwave imaging. Different wavefront processing are presented, from an immediate use of measured projections to more complex procedures. Both spectral approaches to diffraction tomography and spatial iterative methods for generalized imaging are considered using multi‐incidence of multifrequency techniques for 3D and/or 2D objects. The technology of the so‐called microwave camera is presented for the fast recording of the scattered field with arrays of probes involving one‐ or two‐dimensional sensors at a single frequency or in a broad‐frequency band. Three different systems are depicted: a single‐frequency linear sensor devoted to industrial applications (on‐line transverse control of conveyed products), a single‐frequency planar microwave camera for biomedical applications and research, and a broad‐frequency linear microwave camera for civil engineering applications (detection of the rebars in reinforced concrete strctures). Microwave images obtained experimentally with the three systems are presented on configurations of practical interest for each field of application.