Non-metallic materials and composites are now commonplace in modern vehicle construction, and the need to compute scattering and other electromagnetic phenomena in the presence of material structures has led to the development of new simulation techniques.
This book describes a variety of methods for the approximate simulation of material surfaces, and provides the first comprehensive treatment of boundary conditions in electromagnetics. The genesis and properties of impedance, resistive sheet, conductive sheet, generalised (or higher order) and absorbing (or non-reflecting) boundary conditions are discussed. Applications to diffraction by numerous canonical geometries and impedance (coated) structures are presented, and accuracy and uniqueness issues are also addressed, high frequency techniques such as the physical and geometrical theories of diffraction are introduced, and more than i 30 figures illustrate the results, many of which have not appeared previously in the literature.
Written by two of the authorities m the field, this graduate-level text should be of interest to all scientists and engineers concerned with the analytical and numerical solution of electromagnetic problems.
There have been significant developments in the field of numerical methods for diffraction problems in recent years, and as a result, it is now possible to perform computations with more than ten million unknowns. However, the importance of asymptotic methods should not be overlooked. Not only do they provide considerable physical insight into diffraction mechanisms, and can therefore aid the design of electromagnetic devices such as radar targets and antennas, some objects are still too large in terms of wavelengths to fall in the realm of numerical methods. Furthermore, very low Radar Cross Section objects are often difficult to compute using multiple methods. Finally, objects that are very large in terms of wavelength, but with complicated details, are still a challenge both for asymptotic and numerical methods. The best, but now widely explored, solution for these problems is to combine various methods in so called hybrid methods.
Asymptotic and Hybrid Methods in Electromagnetics is based on a short course, and presents recent developments in the field.
This book begins with an essential background discussion of the many applications and drawbacks for paraxial beams, which is required in the treatment of the complex space theory of spatially localized electromagnetic waves. The author highlights that there is a need obtain exact full-wave solutions that reduce to the paraxial beams in the appropriate limit. Complex Space Source Theory of Spatially Localized Electromagnetic Waves treats the exact full-wave generalizations of all the basic types of paraxial beam solutions. These are developed by the use of Fourier and Bessel transform techniques and the complex space source theory of spatially localized electromagnetic waves is integrated as a branch of Fourier optics. Two major steps in the theory are described as: 1) the systematic derivation of the appropriate virtual source in the complex space that produces the required full wave from the paraxial beam solution and 2) the determination of the actual secondary source in the physical space that is equivalent to the virtual source in the complex space.
The book discusses homogenisation principles and mixing rules for the determination of the macroscopic dielectric and magnetic properties of different types of media. The effects of structure and anisotropy are discussed in detail, as well as mixtures involving chiral and nonlinear materials. High frequency scattering phenomena and dispersive properties are also discussed.
The book includes analysis of special phenomena that the mixing process can cause, such as the difference in character between a mixture and its constituent parts. Mixing results are applied to different materials in geophysics and biology. Reference is also made to the historical perspectives of dielectric modelling. Examples are included throughout the text.
Aimed at students with research interests in electromagnetics or materials science, the book is also useful as a textbook in universities, as a handbook of mixing principles, and as a sourcebook for composite material design.
This book introduces the powerful Finite-Difference Time-Domain method to students and interested researchers and readers. An effective introduction is accomplished using a step-by-step process that builds competence and confidence in developing complete working codes for the design and analysis of various antennas and microwave devices. This book will serve graduate students, researchers, and those in industry and government who are using other electromagnetics tools and methods for the sake of performing independent numerical confirmation. No previous experience with finite-difference methods is assumed of readers.
Presents the fundamental techniques of the FDTD method at a graduate level, taking readers from conceptual understanding to actual program development.
Full derivations are provided for final equations.
Includes 3D illustrations to aid in visualization of field components and fully functional MATLAB® code examples.
Completely revised and updated for this second edition, including expansion into advanced techniques such as total field/scattered field formulation, dispersive material modeling, analysis of periodic structures, non-uniform grid, and graphics processing unit acceleration of finite-difference time-domain method.
The geometrical theory of diffraction (GTD) is an efficient method of analysis and design of wave fields. It is widely used in antenna synthesis in microwave, millimetre and infra-red bands, in circuit engineering and laser system design. It is a convenient tool for tackling the problems of wave propagation and scattering at bodies of complex shape. The method combines the simplicity and physical transparency of geometrical optics with high computational accuracy over a wide dynamic range of quantities analysed. The advantage of GTD is particularly pronounced in applications where the wavelength is small compared with the typical size of scatterers, i.e. in situations where the known analytical techniques - variational calculus and numerical analysis - are no longer applicable.
This book painstakingly systematises the ideas underlying GTD, gives a detailed explanation of the modern state of the theory within the bounds of its validity, and elucidates its relationships with other popular asymptotic theories - the methods of physical optics and edge waves.
The book is designed for scientists, engineers and postgraduate students involved in electromagnetics, radio engineering and optical system design.
The continuous development of the Geometrical Theory of Diffraction (GTD), from its conception in the 1950s, has now established it as a leading analytical technique in the prediction of high-frequency electromagnetic radiation and scattering phenomena. Consequently, there is an increasing demand for research workers and students in electromagnetic waves to be familiar with this technique. In this book they will find a thorough and clear exposition of the GTD formulation for vector fields. It begins by describing the foundations of the theory in canonical problems and then proceeds to develop the method to treat a variety of circumstances. Where applicable, the relationship between GTD and other high-frequency methods, such as aperture field and the physical optics approximation, is stressed throughout the text. The purpose of the book, apart from expounding the GTD method, is to present useful formulations that can be readily applied to solve practical engineering problems. To this end, the final chapter supplies some fully worked examples to demonstrate the practical application of the GTD techniques developed in the earlier chapters.
Electromagnetic waves are guided by open structures in a variety of applications at radio, microwave, millimetric and optical frequencies. Examples range from the propogation of radiowaves down the shaft of an oil rig to that of light through an optical fibre. As the guide is open, radiation may also be present, for example from a microstrip-fed patch or a slot antenna. These twin aspects of waveguiding and radiation are in fact closely interwoven and this book is the first to deal with the two by means of a single mathematical formalism.
The treatment develops from intermediate level guided wave electromagnetism through to frontier concepts and theoretical methods for discontinuities in open, hybrid mode 3D structures by way of real detailed problems taken from the fields of microwaves, millimetric waves and integrated optics. Examples include slotted waveguides, step discontinuities in slab waveguides, coupled and truncated ribguides, via holes in open microstrip, and air bridges in open coplanar waveguides. The unifying concept is the fundamental modal approach for both guiding and radiation, developed by the authors during the course of many years of research.
The book is suitable for engineers and scientists dealing with the simulation of integrated planar antennas, millimetric circuits, integrated optics and other general open cylinder structures.
This book describes new, highly effective, rigorous analysis methods for electromagnetic wave problems. Examples of their application to the mathematical modelling of micros trip lines, corrugated flexible waveguides, horn antennas, complex-shaped cavity resonators and periodic structures are considered.
Special attention is paid to energy dissipation effects. Various physical models and methods of analysis of dissipation are described and approximate formulas and computer-based calculation results for dissipation characteristics are given and compared with experimental data. Ways of decreasing dissipation in waveguides and resonators are discussed.
The book will be of interest to physicists and engineers working on the theory and design of microwave and millimetre-wave components and devices. Designers in microwave engineering will find here all the information they need for choosing the correct waveguide (resonator) for a stipulated dissipation characteristic. The numerical algorithms and formulas can be directly applied to CAD systems. The book is also relevant for students of electromagnetism and microwave circuits.
This book is a systematic and detailed exposition of different analytical techniques used in studying two of the canonical problems, the wave scattering by wedges or cones with impedance boundary conditions. It is the first reference on novel, highly efficient analytical-numerical approaches for wave diffraction by impedance wedges or cones. This text includes calculations of the diffraction or excitation coefficients, including their uniform versions, for the diffracted waves from the edge of the wedge or from the vertex of the cone; study of the far-field behavior in diffraction by impedance wedges or cones, reflected waves, space waves from the singular points of the boundary (from edges or tips), and surface waves; and the applicability of the reported solution procedures and formulae to existing software packages designed for solving real-world high-frequency problems encountered in antenna, wave propagation, and radar cross section. This book is for researchers in wave phenomena physics, radio, optics and acoustics engineers, applied mathematicians and specialists in mathematical physics and specialists in quantum scattering of many particles.
This book is an essential resource for researchers involved in designing antennas and RCS calculations. It is also useful for students studying high frequency diffraction techniques. It contains basic original ideas of the Physical Theory of Diffraction (PTD), examples of its practical application, and its validation by the mathematical theory of diffraction. The derived analytic expressions are convenient for numerical calculations and clearly illustrate the physical structure of the scattered field. The text's key topics include: Theory of diffraction at black bodies introduces the Shadow Radiation, a fundamental component of the scattered field; RCS of finite bodies of revolution-cones, paraboloids, etc.; models of construction elements for aircraft and missiles; scheme for measurement of that part of a scattered field which is radiated by the diffraction (so-called nonuniform) currents induced on scattering objects; development of the parabolic equation method for investigation of edge-diffraction; and a new exact and asymptotic solutions in the strip diffraction problems, including scattering at an open resonator.
The cross-section method is an analytical tool used in the design of components required for low-loss, highly efficient transmission of electromagnetic waves in nonuniform waveguides. When the waveguide dimensions are large compared with the wavelength, a fully three-dimensional analysis employing modern numerical methods based on finite element, finite difference, finite integration or transmission line matrix formalisms is practically impossible and the cross-section method is the only feasible analysis technique.
The method is not limited to oversized tubular metallic waveguides, but is employed intensively in areas such as fibre optic communications, antenna synthesis, natural waveguides (submarine, tropospheric and seismic), microwave radio links (Earth or space) and the design of absorbing surfaces and it may also be applied to many acoustic problems. The application of the method in special cases such as cut-off and resonant frequencies is covered, as well as the design of oversized waveguide components such as tapers, bends, polarisers and mode converters. Many useful formulas are given for the practical layout of such transmission line components. The use of computers in the application of the method and problems related to numerical analysis are also covered.
This advanced research monograph is devoted to the Wiener-Hopf technique, a function-theoretic method that has found applications in a variety of fields, most notably in analytical studies of diffraction and scattering of waves. It provides a comprehensive treatment of the subject and covers the latest developments, illustrates the wide range of possible applications for this method, and includes an extensive outline of the most powerful analytical tool for the solution of diffraction problems.
This will be an invaluable compendium for scientists, engineers and applied mathematicians, and will serve as a benchmark reference in the field of theoretical electromagnetism for the foreseeable future.