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Recent emphasis upon the importance of the physical environment has made science and the public even more cog nizant of the many components of the biosphere. While much attention has been given to ionizing electromagnetic stimuli which causes blatant and unalterable changes in biological systems, relatively little research has been concerned with those electromagnetic signals whose frequencies overlap with time-varying processes in living organisms. Extremely low frequency (ELF) electromagnetic fields can occur as waves between about I Hz to 100 Hz or as short pulses within this range of very low frequency (VLF) and higher frequency sources. The natural occurrence of ELF signals is associated with weather changes, solar disturbances and geophysical ionospheric perturbations. Man-made sources have also been reported. Certain physical properties of ELF signals make them excellent candidates for biologically important stimuli. Unlike many other weather components, ELF signals have the capacity to penetrate structures which house living organ isms. ELF wave configurations allow long distance propaga tional capacities without appreciable attenuation of inten sity, thus making them antecedent stimuli to approaching weather changes. Most importantly, ELF signals exhibit the frequencies and wave forms of bio-electrical events that occur within the brain and body. Thus resonance inter actions between animal and nature become attractive possi bilities.
International Series of Monographs in Electromagnetic Waves, Volume 3: Electromagnetic Waves in Stratified Media provides information pertinent to the electromagnetic waves in media whose properties differ in one particular direction. This book discusses the important feature of the waves that enables communications at global distances. Organized into 13 chapters, this volume begins with an overview of the general analysis for the electromagnetic response of a plane stratified medium comprising of any number of parallel homogeneous layers. This text then explains the reflection of electromagnetic waves from planar stratified media. Other chapters consider the oblique reflection of plane electromagnetic waves from a continuously stratified medium. This book discusses as well the fundamental theory of wave propagation around a sphere. The final chapter deals with the theory of propagation in a spherically stratified medium. This book is a valuable resource for electrical engineers, scientists, and research workers.
Terrestrial Propagation of Long Electromagnetic Waves deals with the propagation of long electromagnetic waves confined principally to the shell between the earth and the ionosphere, known as the terrestrial waveguide. The discussion is limited to steady-state solutions in a waveguide that is uniform in the direction of propagation. Wave propagation is characterized almost exclusively by mode theory. The mathematics are developed only for sources at the ground surface or within the waveguide, including artificial sources as well as lightning discharges. This volume is comprised of nine chapters and begins with an introduction to the fundamental concepts of wave propagation in a planar and curved isotropic waveguide. A number of examples are presented to illustrate the effects of an anisotropic ionosphere. The basic equations are summarized and plane-wave reflection from a dielectric interface is considered, along with the superposition of two obliquely incident plane waves. The properties of waveguide boundaries are implicitly represented by Fresnel reflection coefficients. Subsequent chapters focus on boundaries of the terrestrial guide; lightning discharges as a natural source of extremely-low-frequency and very-low-frequency radiation; and the mode theory for waves in an isotropic spherical shell. This book will be a useful resource for students and practitioners of physics.
The participation of such diverse scientific and technical disciplines as meteorology, astronomy, atmospheric electricity, ionospheric and magnetospheric physics, electromagnetic wave propagation, and radio techniques in the research of atmospherics means that results are published in scientific papers widely spread throughout the literature. This Handbook collects the latest knowledge on atmospherics and presents it in two volumes. Each chapter is written by an expert in his or her field. Topics include the physics of thunderclouds, thunder, global atmospheric electric currents, biological aspects of sferics, and various space techniques for detecting lightning within our own atmosphere as well as in the atmospheres of other planets. Up-to-date applications and methodology are detailed. Volumes I and II offer a comprehensive discussion that together will serve as an important resource for practitioners, professionals, and students alike.
An introduction to RF propagation that spans all wireless applications This book provides readers with a solid understanding of the concepts involved in the propagation of electromagnetic waves and of the commonly used modeling techniques. While many books cover RF propagation, most are geared to cellular telephone systems and, therefore, are limited in scope. This title is comprehensive-it treats the growing number of wireless applications that range well beyond the mobile telecommunications industry, including radar and satellite communications. The author's straightforward, clear style makes it easy for readers to gain the necessary background in electromagnetics, communication theory, and probability, so they can advance to propagation models for near-earth, indoor, and earth-space propagation. Critical topics that readers would otherwise have to search a number of resources to find are included: * RF safety chapter provides a concise presentation of FCC recommendations, including application examples, and prepares readers to work with real-world propagating systems * Antenna chapter provides an introduction to a wide variety of antennas and techniques for antenna analysis, including a detailed treatment of antenna polarization and axial ratio; the chapter contains a set of curves that permit readers to estimate polarization loss due to axial ratio mismatch between transmitting and receiving antennas without performing detailed calculations * Atmospheric effects chapter provides curves of typical atmospheric loss, so that expected loss can be determined easily * Rain attenuation chapter features a summary of how to apply the ITU and Crane rain models * Satellite communication chapter provides the details of earth-space propagation analysis including rain attenuation, atmospheric absorption, path length determination and noise temperature determination Examples of widely used models provide all the details and information needed to allow readers to apply the models with confidence. References, provided throughout the book, enable readers to explore particular topics in greater depth. Additionally, an accompanying Wiley ftp site provides supporting MathCad files for select figures in the book. With its emphasis on fundamentals, detailed examples, and comprehensive coverage of models and applications, this is an excellent text for upper-level undergraduate or graduate students, or for the practicing engineer who needs to develop an understanding of propagation phenomena.
In 1873 Scottish physicist James Clerk Maxwell first advanced the idea that there might be electromagnetic waves that were similar to light waves, a startling concept to the scientists of his day. About 13 years later, German physicist Heinrich Hertz demonstrated in his laboratory that electromagnetic radiation did indeed exist. But it was not until after Hertz's death that a young Italian named Guglielmo Marconi got the idea for a practical communications system based on Hertz's work. Marconi was surprised and disappointed that the Italian government was not interested in his newly discovered wireless communications system, and thus he took his equipment to England. From that point on, the wireless became identified with Britain. From these beginnings, wireless radio became the basis of a revolution that has resulted in the satellite communications of today. This history first looks at Marconi's invention and then explores its many applications, including marine radio, cellular telephones, police and military uses, television and radar. Radio collecting is also discussed, and brief biographies are provided for the major figures in the development and use of the wireless.