Coetzee, S.L.; (2007) Narrow band high resolution radar imaging. Doctoral thesis , University of London.

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Abstract

Most modern radar systems use a monostatic configuration and exploit wide bandwidth to achieve high down range resolution used for target detection and classification. However increasing pressure on occupancy of the radio spectrum and the requirement for ever more accurate target classification poses serious challenges to future radar designs. Techniques based on narrow band radar are thus being investigated as a mean of reducing spectral occupancy. This approach can be coupled with the use of a multiple radar (multistatic) geometry to provide a potentially powerful technique for improving target detection and classification even beyond that of conventional systems. A multistatic topography allows the application of tomographic techniques for target imaging. Tomography is a process by which a two-dimensional cross-sectional image of an object is obtained via illumination from a variety of differing angles in a variety of differing planes. In radar tomography observations from multiple radar locations enable a three dimensional projection in Fourier space. In this way a three dimensional image of an object can be constructed using techniques such as Backprojection. The use of a narrow band waveform in multistatic radar tomography trades resolution achieved by bandwidth for resolution achieved by spatially diverse angular imaging. This thesis reports a detailed investigation into a range of narrow band, multistatic geometries and techniques to obtain high resolution imaging of moving targets. Images processed using Synthetic Aperture Radar (SAR) and Inverse SAR (ISAR) configurations, modified to emulate multistatic narrow band configurations, have been investigated for both real and simulated data. The effect on the spatial resolution due to masking, ambiguity and coherency of targets consisting of both sparse and dense scatterers was analysed under a range of conditions. A cross range resolution of A/4 was achieved using simulated data. This analysis was also extended to the case of real data of typical ground targets. In this situation the data is inevitably significantly affected by noise but a resolution of A/2 was achieved. This study concludes with a comparison of modeled narrow band system performance with theoretical predictions leading to a preliminary assessment of the capability of the narrow band radar tomographic imaging technique for potential applications.

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