Electromagnetic Signals deals with the practical applications of nonsinusoidal electromagnetic waves or carrier free radars, ultrawideband technology and large relative bandwidth technology. The book is unique since it deals with a number of current conventional radar problems along with proposed solutions.
The propagation of waves along and across the boundary between two media with different characteristic velocities is much more complicated when the source is on or near the boundary than when it is far away and the incident waves are plane. Examples of waves generated by localized sources near a boundary are the electromagnetic waves from the currents in a dipole on the surface of the earth and the seismic waves from a slip event in a fault in the earth's crust like the San Andreas fault in California. Both involve a type of surface wave that is called a lateral wave in electro magnetics and a head wave in seismology. Since the two are analogous and the latter is more easily visualized, it is conveniently used here to introduce and describe this important type of surface wave using the data of Y. Ben Zion and P. Malin ("San Andreas Fault Zone Head Waves Near Parkfield, CA," Science 251, 1592-1594, 29 March 1991).
Maxwell's equations have been the basis of electromagnetic theory for a century. They were very successful in providing solutions with sinusoidal time variation, but these solutions are outside the causality law and the conservation law for energy. Signal solutions, which satisfy these two laws, generally do not exist, but can be obtained by adding a term for magnetic dipole currents to Maxwell's equations. Such currents are caused by the rotation of magnetic dipoles, ranging from the hydrogen atom to the magnetic compass needle. Many computer plots of the time variation of electric and magnetic field strengths excited by signals are given in this useful book.
For courses in Electromagnetic Fields & Waves. Electromagnetic Waves continues the applied approach used in the authors' successful Engineering Electromagnetics. The second book is appropriate for a second course in Electromagnetics that covers the topic of waves and the application of Maxwell's equations to electromagnetic events.
Most texts on electromagnetic theory follow the classical approach of steady state solutions of Maxwell's equations. In Interstellar Propagation of Electromagnetic Signals, the authors, H. Harmuth and K. Lukin, point out the deficiencies in Maxwell's theory and present an exciting new way of obtaining transient or signals solutions. This book can be used by researchers, graduate students and scientists in the areas of physics, astrophysics, astronomy and electromagnetic theory or electromagnetics.
We live in a world of waves. The Earth shakes to its foundations, the seas and oceans tremble incessantly, sounds reverberate through land, sea, and air. Beneath the skin, our brains and bodies are awash with waves of their own, and the Universe is filled by a vast spectrum of electromagnetic radiation, of which visible light is the narrowest sliver. Casting the net even wider, there are mechanical waves, quantum wave phenomena, and the now clearly detected gravitational waves. Look closer and deeper and more kinds of waves appear, down to the most fundamental level of reality. This Very Short Introduction looks at all the main kinds of wave, their sources, effects, and uses. Mike Goldsmith discusses how wave motion results in a range of phenomena, from reflection, diffraction, interference, and polarization in the case of light waves to beats and echoes for sound. All waves, however different, share many of the same features, and, as Goldsmith shows, for all their complexities many of their behaviours are fundamentally simple. ABOUT THE SERIES: The Very Short Introductions series from Oxford University Press contains hundreds of titles in almost every subject area. These pocket-sized books are the perfect way to get ahead in a new subject quickly. Our expert authors combine facts, analysis, perspective, new ideas, and enthusiasm to make interesting and challenging topics highly readable.
A unified treatment of the generation and analysis of brain-generated electromagnetic fields. In Brain Signals, Risto Ilmoniemi and Jukka Sarvas present the basic physical and mathematical principles of magnetoencephalography (MEG) and electroencephalography (EEG), describing what kind of information is available in the neuroelectromagnetic field and how the measured MEG and EEG signals can be analyzed. Unlike most previous works on these topics, which have been collections of writings by different authors using different conventions, this book presents the material in a unified manner, providing the reader with a thorough understanding of basic principles and a firm basis for analyzing data generated by MEG and EEG. The book first provides a brief introduction to brain states and the early history of EEG and MEG, describes the generation of electromagnetic fields by neuronal activity, and discusses the electromagnetic forward problem. The authors then turn to EEG and MEG analysis, offering a review of linear and matrix algebra and basic statistics needed for analysis of the data, and presenting several analysis methods: dipole fitting; the minimum norm estimate (MNE); beamforming; the multiple signal classification algorithm (MUSIC), including RAP-MUSIC with the RAP dilemma and TRAP-MUSIC, which removes the RAP dilemma; independent component analysis (ICA); and blind source separation (BSS) with joint diagonalization.
The book describes the features that vibrations and waves of all sorts have in common and includes examples of mechanical, acoustical, and optical manifestations of these phenomena that unite various parts of physics. The main emphasis, however, is on the oscillatory aspects of the electromagnetic field—that is, on the vibrations, waves, radiation, and the interaction of electromagnetic waves with matter. This text was developed over a five-year period during which its authors were teaching the subject. It is the culmination of successful editions of class notes and preliminary texts prepared for their one-semester course at MIT designed for sophomores majoring in physics but taken by students from other departments as well. The book describes the features that vibrations and waves of all sorts have in common and includes examples of mechanical, acoustical, and optical manifestations of these phenomena that unite various parts of physics. The main emphasis, however, is on the oscillatory aspects of the electromagnetic field—that is, on the vibrations, waves, radiation, and the interaction of electromagnetic waves with matter. The content is designed primarily for the use of second or third year students of physics who have had a semester of mechanics and a semester of electricity and magnetism. The aim throughout is to provide a mathematically unsophisticated treatment of the subject, but one that stresses modern applications of the principles involved. Descriptions of devices that embody such principles—such as seismometers, magnetrons, thermo-nuclear fusion experimental configurations, and lasers—are introduced at appropriate points in the text to illustrate the theoretical concepts. Many illustrations from astrophysics are also included.
As a slag heap, the result of strip mining, creeps closer to his house in the Ohio hills, fifteen-year-old M. C. is torn between trying to get his family away and fighting for the home they love.