Reconstruction of the SAR Image for a Tree Using the W-Band SAR System

The advantages of 77GHz-FMCW (Frequency Modulation Continuous Wave) RADAR, including its compact antenna size and short wavelength, have led to an increase in research demand. In particular, W-band SAR (Synthetic Aperture RADAR) utilizing 77GHz-FMCW has been applied in various fields, such as the automotive industry. However, challenges remain in the reconstruction of SAR image for a tree and the construction of the W-band SAR system. This study introduces a method for the construction of a stable W-band SAR system and a technique for the reconstruction of a SAR image of a tree. In order to construct the stable W-band SAR system, a 5-meter linear rail with the 77GHz-FMCW RADAR was accurately synchronized. In order to reconstruct the SAR image of the tree, a novel geometry and an environment of the experiment were used. A LiDAR depth map was used for precise calculation of the distance between the RADAR and the target. Coordinates of the LiDAR and the RADAR were matched, by using the corner reflector as a reference point. The quality of the constructed SAR system was evaluated using SAR image quality assessment parameters such as 3-dB resolution, PSLR (Peak Side Lobe Ratio), and ISLR (Integrated Side Lobe Ratio). By using the geometry and the environment of the constructed W-band SAR system, the SAR image of the tree was reconstructed. We compared the SAR image reconstructed by our proposed method with that obtained from the conventional method, using similarity metrics such as SSIM (Structured Similarity Index Measure) and FSIM (Feature Similarity Index Measure) for assessment. These results demonstrate the feasibility and verification of utilizing the constructed W-band SAR system and the reconstruction of the SAR image of the tree.