A Decoupling and Dimension Dividing Multi-parameter Estimation Method for Cross-band SAR Scattering Centers

Microwave photonics radar generates cross-band signals with large bandwidth, providing a basis for precise electromagnetic characteristics description and accurate identification of targets. Meanwhile, a corresponding electromagnetic model parameter extraction method is urgently required in the case of large-bandwidth and wide-angle. For the same scene, the amount of return signals will increase considerably in cross-band condition comparing with narrow-bandwidth condition. Furthermore, the signals under cross-band condition may exhibit complex range-azimuth coupling. Under such a condition, it is of difficulty to estimate high dimensional physical parameters of scattering centers in the scene from return signals. To solve this problem, a multi-parameter estimation of cross-band SAR scattering centers method is proposed. The Polar Format Algorithm (PFA) and the attributed scattering center model are combined to construct a two-dimensional decoupled wavenumber domain model. With this scattering model, the estimation procedure is transformed into an optimization problem with multiple variables. This complex multi-variable optimization problem is divided into a set of single variable optimization problems by using the Coordinate Descent Algorithm (CDA). The separation effectively reduces dictionary dimensions and estimation complexity. Moreover, the Hooke-Jeeves algorithm is introduced to enhance estimation accuracy in each single variable optimization problem. Consequently, the proposed estimator for scattering parameters is not only efficient, but also accurate. The structure and location of each scattering center can be identified according to the parameter estimation results. Simulation results confirm the validity of the proposed method.