Radar imaging, as understood here, involves target recognition, i.e. the determination of the detailed properties of an object (size, shape, structure and composition, and also location and speed) from radar echoes returned by it. Advanced approaches are required for this, and several of recent interest are discussed in this book. They include mathematical inverse-scattering techniques based on the solution of integral equations; use of the singularity expansion method (SEM), related to the resonance scattering theory (RST), in which the pattern of resonance-frequency location in the complex frequency plane can be employed to characterize a given radar target; and the use of polarization information. Finally, the measurement of radar cross-sections is described.
Table of Contents1 Introduction.- References.- 2 Radar Polarimetry: Applications to Radar Systems.- 2.1 Polarization Behavior of Different Radar Objects.- 2.2 Some Implementation Aspects.- 2.2.1 Dual-Polarization Radar Configurations.- 2.2.2 Polarization Adaptation.- 2.2.3 Radar System Requirements.- 2.3 Optimum Radar Receivers for Target Detection in the Clear.- 2.3.1 Some Optimum Receiver Structures.- 2.3.2 Some Remarks on Performance Evaluation.- 2.4 Evaluation of Polarimetric Doppler Resolution Through Cramèr-Rao Bounds.- 2.4.1 Signal Modeling.- 2.4.2 Cramèr-Rao Bound and Maximum Likelihood Estimation.- 2.5 Adaptive Polarization Cancellation of Partially Polarized Disturbance.- 2.5.1 Improving Signal/Disturbance Ratio Through Polarization Adaptation.- 2.5.2 Polarization Adaptation for Disturbance Cancellation.- 2.5.3 Results on Adaptive Polarization Cancellation of Partially Polarized Disturbance.- 2.6 Conclusions and Perspectives.- References.- 3 Fine Resolution of Radar Targets.- 3.1 Connection Between Creeping Waves and the Singularity Expansion Method.- 3.1.1 Watson Transformation.- 3.1.2 Singularity Expansion Method: Conducting Targets.- 3.1.3 Dielectric Targets.- 3.2 Surface Wave Resonances on Smooth Targets of General Shape.- 3.2.1 Finite Circular-Cylindrical Cavity.- 3.2.2 Resonances of Conducting Finite Cylinders and Prolate Spheroids.- 3.2.3 Phase Matching of Surface Waves on Conducting Spheroids.- 3.3 Application to Inverse Scattering.- 3.3.1 Radar Spectroscopy.- 3.3.2 The Inverse Scattering Problem for a Coated Conducting Sphere.- 3.3.3 Transient Observation of Resonance Frequencies..- 3.4 Conclusions.- References.- 4 A Unified Theory of Multidimensional Electromagnetic Vector Inverse Scattering Within the Kirchhoff or Born Approximation.- 4.1 Integral Representations for Electromagnetic Scattering by Perfectly Conducting and Dielectric Scatterers.- 4.2 Linearization in Terms of the Born or Kirchhoff Approximation for Plane Wave Incidence.- 4.3 Dyadic Backpropagation in Terms of the Generalized Vector Holographic Fields.- 4.4 Solution of the Linearized Electric Vector Porter-Bojarski Equation in the Frequency Diversity Mode.- 4.4.1 Dielectric Scatterer Within the Born Approximation.- 4.4.2 Perfectly Conducting Scatterer Within the Kirchhoff Approximation.- 4.5 Numerical Simulations.- 4.6 Conclusions.- 4.A Some Properties of Singular Functions.- 4.B Computation of the Generalized Vector Holographic Field in Terms of the Scattering Amplitude.- References.- 5 The Measurement of Radar Cross Section.- 5.1 Measurement Theory.- 5.1.1 Calibration of Measurements.- 5.2 The OSU Measurement Range.- 5.2.1 Compact Range Architecture.- 5.2.2 Reflector Types and Trade Offs.- 5.2.3 The Feed.- 5.2.4 Test Target Support.- 5.2.5 Instrumentation.- 5.2.6 Range Sensitivity.- 5.3 Performance Analysis.- 5.3.1 Direction of Arrival.- 5.3.2 Near Field Imaging.- 5.3.3 Conclusions.- 5.4 Analysis of RCS Measurements.- 5.4.1 Frequency Domain Techniques.- 5.4.2 Aspect Angle Domain Processing.- References.