Bøger af Yuriy M. Penkin

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 "e;think. "e; 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 "e;discoveries.

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.

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 explores the foundations of the theory of thin impedance vibrator antennas, and their uses, aiming to widen the boundaries of the impedance vibrator antennas application in complex modern radio-and-electronic systems and devices.