Yuriy M. Penkin – författare

The rapid and impressive results obtained through the application of numerical methods of analysis to electrodynamics created the rather false impression (es- cially to inexperienced engineers) that all problems were solved long ago or that some of them were not solved because one lacked suf?cient time. However, it is suf?cient to formulate these problems clearly, to give the task to a programmer to create the corresponding program, and to let a computer “think. ” It is only left for an engineer to make the corresponding plots and to explain calculation results if the latter do not agree with existing physical notions. However, de?nite conf- mity to natural laws starts inevitably to appear while realizing this sequence of steps: the problem is prepared for calculations more thoroughly—the probability to obtain the correct answer is higher, and the obtained information is richer and more interesting—the calculated algorithm is simpler; and as expenditure of calculation time is less, correspondingly, the problems to solve effectively are more complex. Theproblemformulationisnotonlycompilationofinitialequationsandanumerical algorithm. It is necessary to foresee a qualitative character of the obtained results and expected order of values, to reveal the peculiarities of the searched solution, complicating its numerical realization and, as a result, choosing the known solution algorithm or working out a new one. If this work has not been done properly, then unexpected anomalies may appear during the numerical calculation process, and the results can be the basis for the most sensational “discoveries.

The book is devoted to exploring the foundations of the theory of thin impedance vibrator antennas. The text provides a continuation of the classic theory of thin perfectly conducting vibrators. Many consider impedance conception one of the most universal models in the theory of wave processes, as it informs such a wide spectrum of uses in solving practical problems of electrodynamics. This topic provides an opportunity to further search analytical solutions, allowing a simplification of the mathematical formulation of the boundary problem. The theory strives to widen the boundaries of the impedance vibrator antennas application in complex modern radio-and-electronic systems and devices. The results of much original research conducted by the authors will be useful for practicing engineers and designers of antenna and waveguide systems.The book is written in an academic style, and can be used to teach students and post graduates about radiotechnical and radiophysical specialities. The conclusion of the book lists many actual applied problems, which can provide inspiration for several potential PhD projects.Topics covered in this book are:•general questions of the theory of impedance vibrators in the spatial-frequency representation•electromagnetic waves radiation by impedance vibrators in free space and material mediums•electromagnetic waves radiation by impedance vibrators in material mediums over the perfectly conducting plane•electromagnetic waves scattering by irregular impedance vibrators in free space•generalized method of induced electromotive forces for investigation of the characteristics of impedance vibrators•radiation of electromagnetic waves by radial impedance vibrators on the perfectly conducting sphere•electromagnetic waves scattering by impedance vibrators in the rectangular waveguide

The book is devoted to exploring the foundations of the theory of thin impedance vibrator antennas. The text provides a continuation of the classic theory of thin perfectly conducting vibrators. Many consider impedance conception one of the most universal models in the theory of wave processes, as it informs such a wide spectrum of uses in solving practical problems of electrodynamics. This topic provides an opportunity to further search analytical solutions, allowing a simplification of the mathematical formulation of the boundary problem. The theory strives to widen the boundaries of the impedance vibrator antennas application in complex modern radio-and-electronic systems and devices. The results of much original research conducted by the authors will be useful for practicing engineers and designers of antenna and waveguide systems.The book is written in an academic style, and can be used to teach students and post graduates about radiotechnical and radiophysical specialities. The conclusion of the book lists many actual applied problems, which can provide inspiration for several potential PhD projects.Topics covered in this book are:•general questions of the theory of impedance vibrators in the spatial-frequency representation•electromagnetic waves radiation by impedance vibrators in free space and material mediums•electromagnetic waves radiation by impedance vibrators in material mediums over the perfectly conducting plane•electromagnetic waves scattering by irregular impedance vibrators in free space•generalized method of induced electromotive forces for investigation of the characteristics of impedance vibrators•radiation of electromagnetic waves by radial impedance vibrators on the perfectly conducting sphere•electromagnetic waves scattering by impedance vibrators in the rectangular waveguide

This book discusses the problem of electromagnetic wave excitation in spatial regions with spherical boundaries and the accurate mathematical modeling based on numerical and analytical methods to significantly reduce the time required for developing new antenna devices. It particularly focuses on elements and systems on mobile objects of complex shape that are made of new technological materials. The experimental development of such devices and systems is an extremely time-consuming, lengthy, and expensive process. The book is intended for senior and postgraduate students and researchers working in the fields of radiophysics, radio engineering and antenna design. The authors assume that readers understand the basics of vector and tensor analysis, as well as the general theory of electrodynamics. The original results presented can be directly used in the development of spherical antennas and antenna systems for the mobile objects.The book addresses problems concerning the construction of Green’s functions for Hertz potentials in electrodynamic volumes with spherical boundaries, and solves these clearly and concisely. It also uses specific examples to analyze areas where the results could potentially be applied. The book covers the following topics:· excitation of electromagnetic fields in coordinate electrodynamic volumes;· Green’s functions for spherical resonators;· Green’s functions for infinite space outside of spherical scatterers;· electromagnetic fields of dipole radiators on spherical scatterers;· electromagnetic fields of thin radial impedance vibrators on perfectly conducting spheres;· electrodynamic characteristics of narrow slots in spherical surfaces;· multi-element and combined vibrator-slot radiators on spherical surfaces.

The book presents solutions to a complex of internal and external problems of electromagnetics associated with the development of theory, construction of mathematical models and the development of rigorous methods for calculating the electrodynamic characteristics of combined vibrator-slot structures. The solutions of problems for determining the characteristics of impedance vibrator and slot radiators with arbitrary geometric and electrophysical parameters presented in the monograph were obtained within the framework of the unified methodological approach to construct asymptotic solutions of integral equations on currents and their systems. This approach made it possible to study a number of new combined vibrator-slot structures. The research results reveal the possibilities of using such structures as basic elements in the creation of modern antenna-waveguide devices operating in the ranges from meter to millimeter wavelengths, with new technical characteristics and functional purpose. The book is intended for senior and postgraduate students and researchers working in the fields of radiophysics, radio engineering and antenna-feeder design.The book covers the following topics:•excitation of electromagnetic waves in volumes with coordinate boundaries;•general issues of the theory of thin impedance vibrators and narrow slots in a spatial-frequency representation;•solution of current equations for isolated vibrator and slot scatterers;•combined radiating vibrator-slot structures in rectangular waveguide;•T-junctions of rectangular waveguides with vibrator-slot structures in coupling areas;•waveguide radiation of the combined vibrator-slot structures;•combined vibrator-slot structures located on a perfectly conducting sphere;•combined vibrator-slot Radiators in antenna arrays;•ultrawideband vibrator-slot structures;

The book presents solutions to a complex of internal and external problems of electromagnetics associated with the development of theory, construction of mathematical models and the development of rigorous methods for calculating the electrodynamic characteristics of combined vibrator-slot structures. The solutions of problems for determining the characteristics of impedance vibrator and slot radiators with arbitrary geometric and electrophysical parameters presented in the monograph were obtained within the framework of the unified methodological approach to construct asymptotic solutions of integral equations on currents and their systems. This approach made it possible to study a number of new combined vibrator-slot structures. The research results reveal the possibilities of using such structures as basic elements in the creation of modern antenna-waveguide devices operating in the ranges from meter to millimeter wavelengths, with new technical characteristics and functional purpose. The book is intended for senior and postgraduate students and researchers working in the fields of radiophysics, radio engineering and antenna-feeder design.The book covers the following topics:•excitation of electromagnetic waves in volumes with coordinate boundaries;•general issues of the theory of thin impedance vibrators and narrow slots in a spatial-frequency representation;•solution of current equations for isolated vibrator and slot scatterers;•combined radiating vibrator-slot structures in rectangular waveguide;•T-junctions of rectangular waveguides with vibrator-slot structures in coupling areas;•waveguide radiation of the combined vibrator-slot structures;•combined vibrator-slot structures located on a perfectly conducting sphere;•combined vibrator-slot Radiators in antenna arrays;•ultrawideband vibrator-slot structures;