Utilizing Polarization Diversity in GBSAR Data-Based Object Classification.

In recent years, the development of intelligent sensor systems has experienced remarkable growth, particularly in the domain of microwave and millimeter wave sensing, thanks to the increased availability of affordable hardware components. With the development of smart Ground-Based Synthetic Aperture Radar (GBSAR) system called GBSAR-Pi, we previously explored object classification applications based on raw radar data. Building upon this foundation, in this study, we analyze the potential of utilizing polarization information to improve the performance of deep learning models based on raw GBSAR data. The data are obtained with a GBSAR operating at 24 GHz with both vertical (VV) and horizontal (HH) polarization, resulting in two matrices (VV and HH) per observed scene. We present several approaches demonstrating the integration of such data into classification models based on a modified ResNet18 architecture. We also introduce a novel Siamese architecture tailored to accommodate the dual input radar data. The results indicate that a simple concatenation method is the most promising approach and underscore the importance of considering antenna polarization and merging strategies in deep learning applications based on radar data.

Near-distance raw and reconstructed ground based SAR data.

Presented data includes two datasets named RealSAR-RAW and RealSAR-IMG. The first one contains unprocessed (raw) radar data obtained using Ground Based Synthetic Aperture Radar (GBSAR), while the second one contains images reconstructed using Omega-K algorithm applied to raw data from the first set. The GBSAR system moves the radar sensor along the track to virtually extend (synthesize) the antenna aperture and provides imaging data of the area in front of the system. The used sensor was a Frequency Modulated Continuous Wave (FMCW) radar with a central frequency of 24 GHz and a 700 MHz wide bandwidth which in our case covered the observed scene in 30 steps with 1 cm step size. The measured (recorded) scenes were made on combinations of three test objects (bottles) made of different material (aluminum, glass, and plastic) in different positions. The aim was to develop a small dataset of GBSAR data useful for classification applications focused on distinguishing different materials from sparse radar data.