scholarly journals Electromagnetic Waves in Variable Media

2012 ◽  
Vol 67 (3-4) ◽  
pp. 111-131
Author(s):  
Ulrich Brosa
Keyword(s):  
Material Properties ◽  
Electromagnetic Waves ◽  
Maxwell's Equations ◽  
Constitutive Relations ◽  
Electromagnetic Energy ◽  
General Solutions ◽  
Optical Instruments ◽  
Dielectric Mirrors ◽  
New Foundations ◽  
Invisibility Cloaks

Two methods are explained to exactly solve Maxwell’s equations where permittivity, permeability, and conductivity may vary in space. In the constitutive relations, retardation is regarded. If the material properties depend but on one coordinate, general solutions are derived. If the properties depend on two coordinates, geometrically restricted solutions are obtained. Applications to graded reflectors, especially to dielectric mirrors, to filters, polarizers, and to waveguides, plain and cylindrical, are indicated. New foundations for the design of optical instruments, which are centered around an axis, and for the design of invisibility cloaks, plain and spherical, are proposed. The variability of material properties makes possible effects which cannot happen in constant media, e.g. stopping the flux of electromagnetic energy without loss. As a consequence, spherical devices can be constructed which bind electromagnetic waves

Terahertz materials for energy harvesting rectenna

2016 ◽  
Author(s):  
◽  
Zachary Thacker
Keyword(s):  
Energy Harvesting ◽  
Material Properties ◽  
Electromagnetic Waves ◽  
Low Frequency ◽  
Electromagnetic Energy ◽  
University Of Missouri ◽  
Nikola Tesla ◽  
Heinrich Hertz ◽  
Quantitative Results ◽  
The University

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Energy collecting antenna have been studied for over a century. Early work performed by Heinrich Hertz and Nikola Tesla focused primarily on the transfer of energy at low frequency electromagnetic waves. The present work studies the possibility for harvesting electromagnetic energy present on earth from both terrestrial and solar sources. In general the energy density available increases with frequency, peaking around the visible portion of the spectrum. Because of the difficulty of converting high frequency signals, the present focus will be on the intermediate Terahertz range where the power density begins to increase. The goal of this work is to support the viability of an energy harvesting rectenna to collect and convert Terahertz frequency electromagnetic energy. The collection of the energy by an antenna is supported through probing frequency dependent material properties required for designing the device. Modelling of materials sensitive to THz waves is confirmed through spectroscopic measurements of fabricated devices. Device design is further supported by showing the relationship between the measured material properties and conversion, or rectification, efficiency. Finally, the concept is proved through quantitative results of THz rectenna measurements.

scholarly journals Abstract Nonconforming Error Estimates and Application to Boundary Penalty Methods for Diffusion Equations and Time-Harmonic Maxwell’s Equations

2018 ◽  
Vol 18 (3) ◽  
pp. 451-475 ◽  
Author(s):  
Alexandre Ern ◽  
Jean-Luc Guermond
Keyword(s):  
Error Analysis ◽  
Error Estimates ◽  
Material Properties ◽  
Maxwell’S Equations ◽  
Vector Fields ◽  
Maxwell's Equations ◽  
Heterogeneous Material ◽  
Test Functions ◽  
Time Harmonic ◽  
New Formulation

AbstractWe devise a novel framework for the error analysis of finite element approximations to low-regularity solutions in nonconforming settings where the discrete trial and test spaces are not subspaces of their exact counterparts. The key is to use face-to-cell extension operators so as to give a weak meaning to the normal or tangential trace on each mesh face individually for vector fields with minimal regularity and then to prove the consistency of this new formulation by means of some recently-derived mollification operators that commute with the usual derivative operators. We illustrate the technique on Nitsche’s boundary penalty method applied to a scalar diffusion equation and to the time-harmonic Maxwell’s equations. In both cases, the error estimates are robust in the case of heterogeneous material properties. We also revisit the error analysis framework proposed by Gudi where a trimming operator is introduced to map discrete test functions into conforming test functions. This technique also gives error estimates for minimal regularity solutions, but the constants depend on the material properties through contrast factors.

scholarly journals Two basic systems of maxwell’s equations in a rotating frame: application in theory of ring laser gyro

2020 ◽  
pp. 64-73
Author(s):  
Evgen Bondarenko
Keyword(s):  
Ring Laser ◽  
Electromagnetic Waves ◽  
Maxwell’S Equations ◽  
Maxwell's Equations ◽  
Plane Waves ◽  
Rotating Frame ◽  
Cylindrical Coordinates ◽  
Laser Gyro ◽  
Component Form ◽  
Velocity Approximation

In the paper, using a linear in angular velocity approximation, two basic well-known systems of Maxwell’s equations in a uniformly rotating frame of reference are considered. The first system of equations was first obtained in the work [L. I. Schiff, Proc. Natl. Acad. Sci. USA 25, 391 (1939)] on the base of use of the formalism of the theory of general relativity, and the second one – in the work [W. M. Irvine, Physica 30, 1160 (1964)] on the base of use of the method of orthonormal tetrad in this theory. In the paper, in the approximation of plane waves, these two vectorial systems of Maxwell’s equations are simplified and rewritten in cylindrical coordinates in scalar component form in order to find the lows of propagation of transversal components of electromagnetic waves in a circular resonator of ring laser gyro in the case of its rotation about sensitivity axis. On the base of these two simplified systems of Maxwell’s equations, the well-known wave equation and its analytical solutions for the named transversal components are obtained. As a result of substitution of these solutions into the first and second simplified systems of Maxwell’s equations, it is revealed that they satisfy only the second one.  On this basis, the conclusion is made that the second system of Maxwell’s equations is more suitable for application in the theory of ring laser gyro than the first one.

Theoretical Meso-Model of Al2O3/ZrO2 Ceramic Response under Compression

2014 ◽  
Vol 601 ◽  
pp. 92-95
Author(s):  
Tomasz Sadowski ◽  
Liviu Marsavina
Keyword(s):  
Grain Boundary ◽  
Material Properties ◽  
Mechanical Model ◽  
Constitutive Relations ◽  
Ceramic Composites ◽  
Theoretical Modeling ◽  
Polycrystalline Structure ◽  
Two Phase

This paper presents theoretical modeling of two-phase ceramic composites subjected to compression. The meso-mechanical model allows for inclusion of all microdefects in the polycrystalline structure that exists at the grain boundary interfaces and inside the grains. The constitutive relations for the Al2O3/ZrO2composite with the gradual degradation of the material properties due to different defects development were formulated.

XXVI.—On a Polarised Light Quantum

1927 ◽  
Vol 46 ◽  
pp. 306-313
Author(s):  
J. M. Whittaker
Keyword(s):  
Electromagnetic Waves ◽  
Maxwell’S Equations ◽  
Maxwell's Equations ◽  
Point Of View ◽  
Light Quantum ◽  
Electric Force ◽  
Polarised Light

In the theory of radiation recently advanced by Sir J. J. Thomson it is supposed that electromagnetic waves and quanta are both present in a beam of light. The quanta, which are responsible for the photoelectric effects, are closed rings of electric force propagated in the direction normal to the plane of the ring. Professor Whittaker has discussed this conception from the point of view of Maxwell's equations, and has shown that it is consistent with them ; or rather with an extension of them in which a magnetic density μ analogous to the electric density ρ is introduced.

ELECTROMAGNETIC WAVES AND MAXWELL'S EQUATIONS

1984 ◽  
pp. 730-750
Author(s):  
George B. Arfken ◽  
David F. Griffing ◽  
Donald C. Kelly ◽  
Joseph Priest
Keyword(s):  
Electromagnetic Waves ◽  
Maxwell’S Equations ◽  
Maxwell's Equations
Sign in / Sign up

Export Citation Format

Share Document