A Compact Microwave Camera Based on Chaotic Excitation Synthetic-Aperture Radar

In this paper, we introduce a compact microwave camera based on a new synthetic-aperture radar (SAR) imaging methodology with potential applications encompassing nondestructive testing (NDT) and security. The imaging methodology defined as chaotic excitation SAR (CESAR) was developed specifically for microwave cameras, where all antennas irradiate a target simultaneously instead of traditional sequential irradiation. The benefit of CESAR is a significant reduction in required RF hardware that is otherwise critical to previous system designs. However, the tradeoff is a degradation of image quality that can be tolerated in some applications. The microwave camera developed for this paper operates in the 23-25 GHz frequency range and is composed of 64 rectangular slot antennas fed with a two-stage power divider network. The divider network is composed of a corporate feed waveguide network and cavity dividers. The camera generates a pseudoplane wave with ~7 dB and 35° of variation in magnitude and phase (compared with a plane wave), respectively. The well-known ω-k SAR algorithm was consequently modified to properly focus images with the new imaging methodology. The experimental imaging results were produced for flaws in polylactic acid and metallic object feature detection, highlighting the camera's suitability for NDT and security applications.