Abstract
In this paper, we investigate the application of Hybrid Representation
in Wide-Angle Synthetic Aperture Radar (WASAR) imaging, addressing the
challenges of achieving sparse representation in the presence of complex
electromagnetic scattering characteristics and highly anisotropic
targets. We utilize a Convolutional Neural Network (CNN) to represent
two-dimensional data within the same subaperture, while employing
dictionary learning for sparse representation across different
subapertures. Convolutional Neural Networks (CNNs) excel at learning
spatial hierarchies and local dependencies in two-dimensional data, but
require a large amount of training data. Isotropic targets within
subapertures can be used for training with conventional SAR data,
whereas anisotropic targets present challenges in obtaining training
samples. To address this, a dictionary for different subapertures is
generated from measurements using dictionary learning, eliminating the
need for additional training data. By integrating these methods, we
propose a novel approach, Hybrid-WASAR, which incorporates two
regularization terms into WASAR imaging and employs the Alternating
Direction Method of Multipliers (ADMM) to iteratively solve the imaging
model. Compared to traditional WASAR imaging techniques, Hybrid-WASAR
not only enhances the accuracy of the reconstructed target backscatter
coefficients, but also effectively reduces sidelobes and noise,
resulting in a significant improvement in overall imaging quality.