Scholarly
    Communications Project


Document Type:Dissertation
Name:Mohamed A. Abdel-Rahman
Email address:mohamed@birch.ee.vt.edu
URN:1998/00056
Title:NUMERICAL RECONSTRUCTION AND APPLICATIONS OF ACOUSTIC AND ELECTROMAGNETIC ULTRA-WIDEBAND LOCALIZED PULSES GENERATED BY DYNAMIC APERTURE ANTENNAS
Degree:Doctor of Philosophy
Department:Electrical and Computer Engineering
Committee Chair: Dr. Ioannis M. Besieris
Chair's email:besieris@vt.edu
Committee Members:Dr. Aicha Elshibini Riad
Dr. W. E. Kohler
Dr. W. A. Scales
Dr. Amr M. Shaarawi
Keywords:Acoustic and Electromagnetic Localized Pulses, Dynamic Aperture Antennas, Huygens and Rayleigh-Sommerfeld Reconstruction, Plasma, Bistatic Scattering, Remote Sensing
Date of defense:December 17, 1997
Availability:Release the entire work immediately worldwide.

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.

List of Attached Files

ch1.pdf ch2.pdf ch3.pdf
ch4.pdf ch5.pdf ch6.pdf
etd.pdf ref.pdf vita.pdf


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