A high-frequency asymptotic technique based on the Uniform Geometric Theory of Diffraction (UTD) is employed for building interior imaging. The analysis is implemented using a ray-tracing technique to account for multiple scattering interactions in a building, along with a set of heuristic diffraction coefficients for dielectric wedges and corners. Imaging of the synthetic aperture radar data is carried out by the conventional fast Fourier transform method to transform to the downrange domain, and combined with a coherent near-zone imaging function for cross-range. Comparisons with experimental data for a scaled-down building model are given to demonstrate the suitability and efficacy of our analysis for through-wall building imaging. The UTD ray mechanisms account for the dominant scattering features observed in the image.

The modeling of antennas on complex platforms is reviewed. The objective is to analyze the modification of the basic antenna performance due to its environment. This includes pattern distortion, antenna to antenna spacial coupling, and radiation hazard predictions. High frequency methods are used to develop computer codes to accomplish these tasks. Several types of generally available codes are discussed.>

Techniques appropriate for low and high frequency numerical evaluation of the scattered fields from complex shapes are discussed. Object size in terms of wavelengths dictates the type of solution to be used. For targets in and just above resonance, the method of moments (MM) is used. The limitation in this case is that the scatterer cannot be too large in terms of the wavelength. For radar targets in the microwave band, the uniform geometrical theory of diffraction (UTD) and modifications thereof form the basis for the computation. This has the basic limitation that the scattering mechanisms need to be known and included in the model. Examples are given for both frequency regimes.>