Non-contact microwave testing system and method for see-through imaging

A method for non-contact see-through imaging of an area under testing, the method comprising the steps of:

• generating electromagnetic waves by a System-in-Package (SiP) subsystem, wherein a stepped frequency continuous wave (SFCW) waveform is generated by the SiP subsystem for non-destructive testing of heterogeneous multi-layered media, including concrete, brick and mortar, ceramic facade, stone claddings, and glass facades;
• transmitting the generated electromagnetic waves to a front-end subsystem through an RF interface, wherein the front-end subsystem comprises at least one transmitter antenna and at least one receiver antenna, wherein the at least one transmitter antenna and the at least one receiver antenna are integrated with a metamaterial-based lens that includes a plurality of concentric periodic split-ring resonators (SRRs) of varying sizes and concentric circular trace lines running in the bottom layer of the lens, wherein the metamaterial-based lens is made from double negative materials (DNG) having the property of negative index to enable sub-wavelength high-resolution imaging;
• transmitting and receiving backscattered signals to the front-end subsystem from the area under testing;
• routing received RF signals to a signal processing subsystem by the SiP subsystem for signal processing and reconstruction of spatial reflectivity of heterogeneous multi-layered media in the area under testing, wherein the reconstruction of spatial reflectivity comprises:
• obtaining, by the signal processing subsystem, wideband frequency domain data S(x, y, z, f) over a source aperture, wherein (x, y, z) represent spatial coordinates, and f represents frequency;
• reconstructing, by the signal processing subsystem, the spatial reflectivity using at least one of:
• piecewise phase addition for each of a plurality of layers of the multi-layered media, wherein an additional phase is added to a collected frequency spectrum in a piecewise manner, one layer at a time, for 3D imaging of the area under testing, including Fresnel transmission coefficients between the layers, or
• deconvolution using dyadic Green's functions of the multi-layered media to include a plurality of reflections and a plurality of attenuations by the plurality of layers, wherein the reconstructed spatial reflectivity provides amplitude and phase components for each x, y, z coordinate for 3D quantitative imaging, including parameters of permittivity and conductivity;
• generating a three-dimensional (3D) image of the area under testing based on the reconstructed spatial reflectivity, wherein the generation of the 3D image comprises combining data from the SiP subsystem and a localization subsystem by the signal processing subsystem to perform 3D image reconstruction and data interpretation schemes, wherein the localization subsystem provides location information for synthesizing a synthetic aperture for the generated 3D image, and wherein the 3D image reconstruction and which is routed to an interface subsystem;
• and
• routing the data interpretation schemes and a reconstructed 3D image by the interface subsystem through wired or wireless transmission to a cloud server or a local tablet personal computer (PC) for a user to visualise the image of the area under testing,
• wherein the method achieves a penetration depth of at least 0.20 m in non-metallic materials and differentiates two distinct objects if a distance of at least 0.01 m separates them, and wherein the method operates in a frequency range from 0.1 GHz to 10 GHz.