Preface 1. Introduction 2. The elastodynamics and its simple solutions 3. Seismic rays and travel times 4. Dynamic ray tracing. Paraxial ray methods 5. Ray amplitudes 6. Ray synthetic seismograms Appendix. Fourier transform, Hilbert transform and analytical signals References Index.

Seismic Ray Theory

Wave propagation in a double negative (DNG) medium, i.e., a medium having negative permittivity and negative permeability, is studied both analytically and numerically. The choices of the square root that leads to the index of refraction and the wave impedance in a DNG medium are determined by imposing analyticity in the complex frequency domain, and the corresponding wave properties associated with each choice are presented. These monochromatic concepts are then tested critically via a one-dimensional finite difference time domain (FDTD) simulation of the propagation of a causal, pulsed plane wave in a matched, lossy Drude model DNG medium. The causal responses of different spectral regimes of the medium with positive or negative refractive indices are studied by varying the carrier frequency of narrowband pulse excitations. The smooth transition of the phenomena associated with a DNG medium from its early-time nondispersive behavior to its late-time monochromatic response is explored with wideband pulse excitations. These FDTD results show conclusively that the square root choice leading to a negative index of refraction and positive wave impedance is the correct one, and that this choice is consistent with the overall causality of the response. An analytical, exact frequency domain solution to the scattering of a wave from a DNG slab is also given and is used to characterize several physical effects. This solution is independent of the choice of the square roots for the index of refraction and the wave impedance, and thus avoids any controversy that may arise in connection with the signs of these constituents. The DNG slab solution is used to critically examine the perfect lens concept suggested recently by Pendry. It is shown that the perfect lens effect exists only under the special case of a DNG medium with $\ensuremath{\epsilon}(\ensuremath{\omega})=\ensuremath{\mu}(\ensuremath{\omega})=\ensuremath{-}1$ that is both lossless and nondispersive. Otherwise, the closed form solutions for the field structure reveal that the DNG slab converts an incident spherical wave into a localized beam field whose parameters depend on the values of $\ensuremath{\epsilon}$ and $\ensuremath{\mu}.$ This beam field is characterized with a paraxial approximation of the exact DNG slab solution. These monochromatic concepts are again explored numerically via a causal two-dimensional FDTD simulation of the scattering of a pulsed cylindrical wave by a matched, lossy Drude model DNG slab. These FDTD results demonstrate conclusively that the monochromatic electromagnetic power flow through the DNG slab is channeled into beams rather then being focused and, hence, the Pendry perfect lens effect is not realizable with any realistic metamaterial.

http://esperia.iesl.forth.gr/~ppm/DALHM/bibliography/LHMpdfs/ziolkowski_PRE64_56625_01.pdf

Wave propagation in media having negative permittivity and permeability

To address the need for fundamental universally valid definitions of exact bandwidth and quality factor (Q) of tuned antennas, as well as the need for efficient accurate approximate formulas for computing this bandwidth and Q, exact and approximate expressions are found for the bandwidth and Q of a general single-feed (one-port) lossy or lossless linear antenna tuned to resonance or antiresonance. The approximate expression derived for the exact bandwidth of a tuned antenna differs from previous approximate expressions in that it is inversely proportional to the magnitude |Z'/sub 0/(/spl omega//sub 0/)| of the frequency derivative of the input impedance and, for not too large a bandwidth, it is nearly equal to the exact bandwidth of the tuned antenna at every frequency /spl omega//sub 0/, that is, throughout antiresonant as well as resonant frequency bands. It is also shown that an appropriately defined exact Q of a tuned lossy or lossless antenna is approximately proportional to |Z'/sub 0/(/spl omega//sub 0/)| and thus this Q is approximately inversely proportional to the bandwidth (for not too large a bandwidth) of a simply tuned antenna at all frequencies. The exact Q of a tuned antenna is defined in terms of average internal energies that emerge naturally from Maxwell's equations applied to the tuned antenna. These internal energies, which are similar but not identical to previously defined quality-factor energies, and the associated Q are proven to increase without bound as the size of an antenna is decreased. Numerical solutions to thin straight-wire and wire-loop lossy and lossless antennas, as well as to a Yagi antenna and a straight-wire antenna embedded in a lossy dispersive dielectric, confirm the accuracy of the approximate expressions and the inverse relationship between the defined bandwidth and the defined Q over frequency ranges that cover several resonant and antiresonant frequency bands.

Impedance, bandwidth, and Q of antennas

The development is given of a model in which the rows or blocks of buildings are viewed as diffracting cylinders lying on the earth. When the buildings are represented as absorbing screens, the propagation process reduces to multiple forward diffraction past a series of screens. Numerical computation of the diffraction effect yields a power-law dependence for the field that is within the measured range. Accounting for diffraction down to street level from the roof tops gives an overall absolute path loss in good agreement with the average measured path loss. >

A theoretical model of UHF propagation in urban environments

A compact representation is given of the electric- and magnetic-type dyadic Green's functions for plane-stratified, multilayered, uniaxial media based on the transmission-line network analog along the aids normal to the stratification. Furthermore, mixed-potential integral equations are derived within the framework of this transmission-line formalism for arbitrarily shaped, conducting or penetrable objects embedded in the multilayered medium. The development emphasizes laterally unbounded environments, but an extension to the case of a medium enclosed by a rectangular shield is also included.

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Multilayered media Green's functions in integral equation formulations

As relevant today as it was when it was first published 20 years ago, this book is a classic in the field. Nowhere else can you find more complete coverage of radiation and scattering of waves. The chapter: Asympotic Evaluation of Integrals is considered the definitive source for asympotic techniques. This book is essential reading for engineers, physicists and others involved in the fields of electromagnetics and acoustics. It is also an indispensable reference for advanced engineering courses.

Radiation and scattering of waves

PULSE GENERATION AND DETECTION: Semiconductor Switching: The Time Evolution of Photonic Crystal Bandgaps (K. Agi et al.). General: Ultrawideband Pulser Technology (D.M. Parkes). ANTENNAS: Impulse Radiating Antennas: Transient Fields of Rectangular Aperture Antennas (S.P. Sulkin). Reflector Impulse Radiating Antennas: Temporal and Spectral Radiation on Boresight of a Reflector Type of Impulse Radiating Antenna (IRA) (D.V. Giri, C.E. Baum). Lens Impulse Radiating Antennas and TEM Horns: Design of the Low-Frequency Compensation of an Extreme-Bandwidth TEM Horn and Lens IRA (M.H. Vogel). Arrays: Transient Arrays (C.E> Baum). General: Some Basic Properties of Antennas Associated with Ultra-wideband Radiation (S.N. Samaddar, E.L. Mokole). PULSE PROPOGATION AND GUIDEANCE: Transient Dielectric Coefficient and Conductance in Dielectric Media in Nonstationary Fields (A. Gutman). SCATTERING THEORY, COMPUTATION, AND MEASUREMENTS: Early Time Signature Analysis of Dielectric Targets Using UWB Radar (S. Cloude et al.). SIGNAL PROCESSING: Time-Frequency Analysis: Feature Extraction from Electromagnetic Backscattered Data Using Joint Time-Frequency Processing (L.C. Trintinalia, H. Ling). Spectral Techniques: The E-Pulse Technique for Dispersive Scatterers (S. Primak et al.). Probabilistic Considerations: Robust Target Identification Using a Generalized Likelihood Ratio Test (J.E. Mooney et al.). General: Error Correction in Transient Electromagnetic Field Measurements Using Deconvolution Techniques (J-Z. Bao et al.). BROADBAND ELECTRONIC SYSTEMS AND COMPONENTS: Systems and Components: Ultra-wideband Sources and Antennas: Present Technology, Future Challenges (W.D. Prather et al.). Ultra-Wideband Radars: Dense Media Penetrating Radar (K. Min, M. Willis, Jr.). Polarimetric Ultra-wideband Radars: Polarimetry in Ultra-wideband Interferometric SEnsing and Imaging (W-M. Boerner, J.S. Verdi). BURIED TARGETS: Analytic Methods for Pulsed Signal Interaction with Layered, Lossy Soil Environments and Buried Objects (L.B. Felsen). 41 additional articles. Index.

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Ultra-wideband, short-pulse electromagnetics 2

Propagation and diffraction of transient fields in non-dispersive and dispersive media.- Integral equation methods for transient scattering.- The singularity expansion method.- Radiation and reception of transients by linear antennas.- A pulsed dipole in the earth.

Transient Electromagnetic Fields

It is shown that the complex Hermite-Gaussian wave functions proposed by Siegman can be generated in a straightforward manner by assigning complex locations to the source points in a multipole expansion of an optical field.

Gaussian beam modes by multipoles with complex source points

Two-dimensional aperiodic tilings are collections of polygons, devoid of any translational symmetries, capable of covering a plane without gaps and overlaps. Although aperiodic, these structures can exhibit order and symmetry in an extended sense. In this paper, we study the radiation properties of planar antenna arrays based on certain categories of two-dimensional aperiodic tilings that illustrate diverse aspects of aperiodic order. Background material on aperiodic tilings and their known electromagnetic properties is reviewed. Results are illustrated to highlight the effects of aperiodic order in the antenna array radiation properties. Potential applications are also envisaged

Leopold B. Felsen

Papers

Radiation and scattering of waves

Ultra-wideband, short-pulse electromagnetics 2

Transient Electromagnetic Fields

Gaussian beam modes by multipoles with complex source points

Radiation properties of planar antenna arrays based on certain categories of aperiodic tilings