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Electromagnetic scattering from fini...

Villegas, Frank Javier.

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Electromagnetic scattering from finite arrays of dielectrically-covered circular cavities in a ground plane.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Electromagnetic scattering from finite arrays of dielectrically-covered circular cavities in a ground plane./
Author:	Villegas, Frank Javier.
Description:	189 p.
Notes:	Chair: Yahya Rahmat-Samii.
Contained By:	Dissertation Abstracts International63-01B
Subject:	Engineering, Electronics and Electrical -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3040187
ISBN:	0493535594

Electromagnetic scattering from finite arrays of dielectrically-covered circular cavities in a ground plane.
Villegas, Frank Javier.

Electromagnetic scattering from finite arrays of dielectrically-covered circular cavities in a ground plane. - 189 p.

Chair: Yahya Rahmat-Samii.

Thesis (Ph.D.)--University of California, Los Angeles, 2002.

In this dissertation, we investigate the scattering characteristics of <italic> finite</italic> one- and two-dimensional arrays of cylindrical cavities embedded within an <italic>infinite</italic> perfect electric conducting ground plane. Fundamental Radar Cross Section features of said arrays are illustrated, with the RCS computed with respect to the scattered (diffracted) field component, not accounting for the source plane-wave reflection from the infinite ground plane. The aperture currents on the finite structure are computed using a hybrid space/spectral-domain method-of-moments (MoM) formulation. The complete set of (TE,TM) cylindrical eigenmodes are used to represent the unknowns. The formulation is quite versatile and efficient, allowing us to include planar stratification and dissimilar cavity depths/radii in the geometry. Several rather interesting results and applications are illustrated. The fundamental scattering characteristics are first shown for the canonical cavity, followed by a study of the mutual coupling behavior between two such cavities in close proximity. Scattering from 1D and 2D arrays is then investigated. The effects of a superstrate layer on the radiation behavior of such finite arrays are also shown. We find that the layer can in fact either enhance or diminish the radiation, depending on the source polarization and layer parameters. It also tends to reduce radiation for grazing angles in all cases. The scattering signature of ‘large’ finite 1D arrays is computed approximately by the introduction of an Active Element Factor defined specifically for scattering problems. Using the MoM solution of a Reduced Window Array, we obtain the far-field patterns of larger structures by simply computing the array factor. Various improvements to this approximation are introduced, which model the localized edge effects to varying degrees of success. Additionally, the use of non-uniform arrays for sidelobe suppression and 2D ‘masked’ structures is illustrated. Finally, an amended version of the core MoM solution is employed to arrive at a novel leaky-wave antenna design methodology. A perturbational procedure is used to compute the leakage constant for an infinite 1D homogeneous array, and this data is tabulated/stored and subsequently used to synthesize a given antenna distribution. The taper calculation also accounts for the varying radiation conductance of the individual array elements, thus yielding a more accurate prototype design

ISBN: 0493535594Subjects--Topical Terms:

1260285
Engineering, Electronics and Electrical

Electromagnetic scattering from finite arrays of dielectrically-covered circular cavities in a ground plane.
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100 1 $a Villegas, Frank Javier. $3 1260312
245 1 0 $a Electromagnetic scattering from finite arrays of dielectrically-covered circular cavities in a ground plane.
300 $a 189 p.
500 $a Chair: Yahya Rahmat-Samii.
500 $a Source: Dissertation Abstracts International, Volume: 63-01, Section: B, page: 0446.
502 $a Thesis (Ph.D.)--University of California, Los Angeles, 2002.
520 $a In this dissertation, we investigate the scattering characteristics of <italic> finite</italic> one- and two-dimensional arrays of cylindrical cavities embedded within an <italic>infinite</italic> perfect electric conducting ground plane. Fundamental Radar Cross Section features of said arrays are illustrated, with the RCS computed with respect to the scattered (diffracted) field component, not accounting for the source plane-wave reflection from the infinite ground plane. The aperture currents on the finite structure are computed using a hybrid space/spectral-domain method-of-moments (MoM) formulation. The complete set of (TE,TM) cylindrical eigenmodes are used to represent the unknowns. The formulation is quite versatile and efficient, allowing us to include planar stratification and dissimilar cavity depths/radii in the geometry. Several rather interesting results and applications are illustrated. The fundamental scattering characteristics are first shown for the canonical cavity, followed by a study of the mutual coupling behavior between two such cavities in close proximity. Scattering from 1D and 2D arrays is then investigated. The effects of a superstrate layer on the radiation behavior of such finite arrays are also shown. We find that the layer can in fact either enhance or diminish the radiation, depending on the source polarization and layer parameters. It also tends to reduce radiation for grazing angles in all cases. The scattering signature of ‘large’ finite 1D arrays is computed approximately by the introduction of an Active Element Factor defined specifically for scattering problems. Using the MoM solution of a Reduced Window Array, we obtain the far-field patterns of larger structures by simply computing the array factor. Various improvements to this approximation are introduced, which model the localized edge effects to varying degrees of success. Additionally, the use of non-uniform arrays for sidelobe suppression and 2D ‘masked’ structures is illustrated. Finally, an amended version of the core MoM solution is employed to arrive at a novel leaky-wave antenna design methodology. A perturbational procedure is used to compute the leakage constant for an infinite 1D homogeneous array, and this data is tabulated/stored and subsequently used to synthesize a given antenna distribution. The taper calculation also accounts for the varying radiation conductance of the individual array elements, thus yielding a more accurate prototype design
590 $a School code: 0031
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790 1 $a Rahmat-Samii, Yahya, $e adviso
791 $a Ph.D
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