Microwave subsurface imaging of dielectric structures using fractal geometries of complementary split ring resonators

Abstract

In this paper, newly proposed complementary split ring resonator (CSRR) structures of fractal geometries are used for microwave imaging of coated dielectric structures in order to detect concealed voids or similar inclusions. The proposed fractal-based CSRR structures are found to display improved sensitivity as compared to the conventional square CSRR sensors of same cross-sectional dimensions, and thus appear to be more appropriate for imaging applications. Detailed analyses of different orders of square Sierpinski fractals have been carried out. Raster scanning of the test region is performed and various parameters such as the magnitude and phase at unloaded resonant frequency, along with the shift in resonant frequency when loaded with the test structure are measured. Furthermore, both qualitative and quantitative images of the test structure are retrieved in terms of all the three measured parameters. Simulation and experimental results demonstrate the applicability of the proposed sensor for microwave imaging.