Imaging chamber based on dual-angle omnidirectionally matched absorbing surface

To meet the demand for scattering-free environment in experiments of inverse scattering-based microwave imaging, we proposed a design scheme of an imaging chamber based on dual-angle omnidirectionally matched absorbing surface. According to the principle of electromagnetically induced transparency and the equivalent medium theory, dual-angle absorbing units were designed on the basis of the periodic arrangement of the ultra-thin absorbing units working at normal and oblique incidence of the electric fields. With a widely used cylindrical architecture, the dual-angle absorbing units were arranged spatially based on the incident angle of the electric field illuminated from the source antenna, forming a 6.9λ-diameter imaging chamber. The simulation results show that the absorbing performance of the constructed imaging chamber is comparable to that of the perfect matched layer. The errors between them are 4.63% and 0.69% when working at oblique and normal incidence conditions, respectively. Imaging experiments based on the constructed imaging chamber verified the effectiveness of the proposed scheme. With the merit of low cost, portability and stability, this imaging chamber is expected to provide technical support for imaging experiments in practical engineering fields such as geological exploration and core measurement.