Publications

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A folded compact range configuration has been developed ant the Sandia National Laboratories` compact range antenna and radar-cross- section measurement facility as a means of performing indoor, environmentally-controlled, far-field simulations of synthetic aperture radar (SAR) measurements of distributed target samples (i.e. gravel, sand, etc.). The folded compact range configuration has previously been used to perform coherent-change-detection (CCD) measurements, which allow disturbances to distributed targets on the order of fractions of a wavelength to be detected. This report describes follow-on CCD measurements of other distributed target samples, and also investigates the sensitivity of the CCD measurement process to changes in the relative spatial location of the SAR sensor between observations of the target. Additionally, this report describes the theoretical and practical aspects of performing interferometric inverse-synthetic-aperture-radar (IFISAR) measurements in the folded compact range environment. IFISAR measurements provide resolution of the relative heights of targets with accuracies on the order of a wavelength. Several examples are given of digital height maps that have been generated from measurements performed at the folded compact range facility.

A novel, folded compact range configuration has been developed at the Sandia National Laboratories compact range antenna and radar cross section measurement facility, operated by the Radar/Antenna Department 2343, as a means of performing indoor, environmentally-controlled, far-field simulations of synthetic aperture radar (SAR) coherent change detection (CCD) measurements. This report describes the development of the folded compact range configuration, as well as the initial set of coherent change detection measurements made with the system. These measurements have been highly successful, and have demonstrated the viability of the folded compact range concept in simulating SAR CCD measurements. It is felt that follow-on measurements have the potential of contributing significantly to the body of knowledge available to the scientific community involved in CCD image generation and processing, and that this tool will be a significant aid in the research and development of change detection methodologies.

While the backscattered field as a function of angular incidence of a plane wave for dihedral corner reflectors having right, acute, and obtuse angles has been studied extensively, it has generally been stated that the RCS of a 90{degree} dihedral corner reflector oriented for maximum backscattered return to a radar is given by the expression {sigma} = 8{pi}a{sup 2}b{sup 2}/{lambda}{sup 2}. The intent of this paper is to present experimental results which demonstrate that not only does the RCS of a dihedral corner reflector oriented for maximum backscattered return differ significantly from this value, but that high range resolution measurements of the dihedral can serve to identify the dominant contributors to the backscattered field. Further, inclusion of these backscattered components in an analytical calculation will allow an accurate calibration model to be generated. 6 refs., 8 figs.