Automotive W-Band SAR System Construction by Using 77 GHz FMCW Radar with Stereo Camera

The W-band Synthetic Aperture Radar (SAR) system can be significantly utilized in autonomous vehicle systems. Accurate estimation of the reference signal phase is essential for reconstructing high-resolution and well-focused SAR images. This necessitates precise distance information between the radar and objects, implying the need for three-dimensional spatial information of the surrounding environment. In this study, we developed an automotive W-band SAR system using a 77 GHz frequency modulation continuous wave radar and a stereo camera. The three-dimensional spatial information of the surroundings was captured using the stereo camera. Optimized six degrees of freedom were achieved using gradient descent based on entropy, allowing for precise alignment of the radar coordinates with the point cloud. Our automotive W-band SAR system successfully reconstructed high-resolution, clear SAR images (vertical cross-sections) of street trees. Compared to traditional SAR systems, our system demonstrated an improvement in structural similarity index by approximately 0.15.