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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...
Using classical array theory this paper presents directivity, sidelobe, and bandwidth performance analysis over narrow and wide bandwidths in the microwave frequency region for several large cylindrical array configurations comprised of panel subarrays. The degree of main beam spreading, grating lobe levels, and directivity loss is presented for several designs involving trade-offs between true time...
Through-wall radar imaging is a challenging area of research due to the complex multi-layer and inhomogeneous structure of building walls. The wall distorts and attenuates the radar signal in a way that is not easy to predict, except in the most simple of cases. In this paper a general periodic model is developed and applied to the imaging algorithm. Periodic dielectric wall models for microwave transmission...
Radar imaging studies of full-scale buildings present serious electromagnetic modeling challenges. The large electrical size makes numerical methods impractical, and the complexity makes ray methods difficult to apply. In this paper we adapt the NEC-basic scattering code (NEC-BSC) [1] to generate simulated radar scattering data for building imaging purposes. The NEC-BSC is based on the uniform geometrical...
Through-wall radar imaging has received much attention recently for discerning objects inside of a building. Most conventional imaging approaches are based on Fourier spectral transforms and/or far-field approximations, such as inverse synthetic aperture radar (ISAR) and tomographic imaging. These methods assume a simple point-scattering model. On the other hand, model-based imaging is a more general...
It is always a challenge to accommodate the large number of antennas needed to meet desired system goals on aircraft. This is especially true on small vehicles where the number of prime locations is minimal. One way to mitigate this situation is to co-locate as many antennas as possible. This paper discusses a frequency selective surface ground plane that can be place on a radome covering a dish antenna...
In this paper, based on a 3D ray-tracing analysis, statistical parameters (i.e. mean excess delay and rms delay spread) for site-specific indoor environments were extracted. The fading statistics of these indoor environments were shown to obey a Weibull distribution. As is well-known, fading statistics are necessary for predicting channel capacity limit and this were presented in the conference
The modeling of complex environments can be very challenging. The uniform geometrical theory of diffraction (UTD) has proven to be very useful in this endeavor especially for large scalable geometries in terms of a wavelength. Most of the time including only a few ray types produces very good engineering results. However, in some cases the need for higher order terms becomes necessary. For example,...
In this paper, an array of closely spaced slot elements has been designed to provide good wide angle scan performance with large bandwidth. The results are stable for a wide range of scan angles and frequencies. The calculated return loss for the design is less than 10 dB for scan angles from 45deg 70deg and for a bandwidth of 40%
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