Title page for ETD etd-02898-04748


Type of Document Dissertation
Author Abdel-Rahman, Mohamed A.
Author's Email Address mohamed@birch.ee.vt.edu
URN etd-02898-04748
Title Numerical Reconstruction and Applications of Acoustic And electromagnetic Ultra-Wideband Localized Pulses Generated by Dynamic Aperture Antennas
Degree PhD
Department Electrical and Computer Engineering
Advisory Committee
Advisor Name Title
Besieris, Ioannis M. Committee Chair
Elshabini-Riad, Aicha A. Committee Member
Kohler, Werner E. Committee Member
Scales, Wayne A. Committee Member
Shaarawi, Amr M. Committee Member
Keywords
  • Acoustic and Electromagnetic Localized Pulses
  • Dynamic Aperture Antennas
  • Huygens and Rayleigh-Sommerfeld Reconstruction
  • Plasma
  • Bistatic Scattering
  • Remote Sensing
Date of Defense 1997-12-17
Availability unrestricted
Abstract

(ABSTRACT)

A study is undertaken of the numerical reconstruction of

acoustic and electromagnetic (EM) localized waves (LWs). The

latter are carrier-free ultra-wideband pulses characterized

by large focusing depths and extended ranges of localization.

Special emphasis is placed on finite energy LWs that can be

generated by dynamic aperture antennas with independently

addressable elements. The reconstruction techniques are based

on Huygens and Rayleigh-Sommerfeld integral I and II

representations, both in the time and frequency domains. In

contradistinction to the Weyl representation,they lend

themselves to the physical realization of space-time aperture

sources capable of generating localized wave solutions

propagating away from the aperture plane. A detailed

comparison of the three reconstruction techniques has been

carried out in connection with LW solutions to the scalar

wave equation, especially with respect to their handling of

acausal components incorporated in the aperture excitation

fields. In addition, a study is presented of the characteristic

properties of LWs propagating through dispersive media modeled

by the Klein-Gordon equation. It is demonstrated that

contrary to expectation, the depletion of the spectral

components of the LW Klein-Gordon field may be slower than

that associated with the free space scalar field. Previous

work by Power et al. [73] is extended by studying the acoustic

bistatic scattering of a modified power spectrum (MPS) pulse

from rigid and compressible spheres. The analysis allows the

extraction of the radius of a sphere from the backscattered

data. Finally, a special class of electromagnetic (EM) LWs,

referred to as azimuthally polarized X waves (APXWs), is

derived and their reconstruction is addressed, both in the

time and frequency domains.

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