The whole spectrum of electromagnetic spectrum and the modern terminology used for various sections of the spectrum are shown in table. The frequency, n, is determined by the oscillator, while the wavelength is determined by the oscillation frequency divided by the velocity of the wave. The comprehensive check questions are based on the objectives. The package has a sequence of 6 models that have both a transient pulse excitation as well as a sine wave excitation. The secondary reflected electric field in the sea in any direction, 2 e. In this chapter, our major focus is on em wave propagation in free space and. The electric field, in turn, generates a magnetic field whose change generates an electric field. The propagation of an electromagnetic wave is described through different parameters. Cbse notes class 12 physics electromagnetic waves and. In any current course on wave propagation, it seemed essential to mention, at least, the quite amazing results being found on exact, solutions for the kortewegde vries equation and related equations. This type of modulation is a fundamental operation in the control of electrooptical devices.
This raytracing business is known as geometrical optics. Solution of wave equation in free space, uniform plane wave propagation, uniform plane waves, the wave equation for conducting medium, wave propagation in lossless medium and in conductive medium, conductors and dielectrics, polarization. When the electrons in a conductor, antenna wire are made to oscillate back and forth, electromagnetic waves em waves are produced. A vertical wire carries an alternating current which generates an electric field. For insulators, the lowest resonant frequency is different from zero. This is an important theory in its own right because explorationists often assume that wave propagation in rocks can be approximated by acoustic theory so that they can simplify their data processing algorithms. These waves required no medium for its propagation. Maxwells work thus unified the domain of electricity, magnetism and light. Presented in two parts, this book takes an analytical approach on the subject and emphasizes new ideas and applications used today. Antennas and wave propagation ec2353 am2015 6th semester.
Its technological use by marconi and others led in due course to the revolution in communication that we are witnessing today. To prevent interference with these services, amateur and experimental transmitters were restricted to the higher hf frequencies, felt to be useless since their ground wave range was limited. Visible light is a commonly studied form of electromagnetic radiation, and exhibits oscillating electric and magnetic fields whose amplitudes and directions are represented by. Electromagnetic waves can be generated by a variety of methods, such as a discharging spark or by an oscillating molecular dipole.
Hertz, in 1885, experimentally demonstrated the existence of electromagnetic waves. Physics of acoustic wave propagation the theory of acoustic wave propagation is now described. The basic principles that enable waves to be propagated transmitted through space are the same today as they were 70 years ago. Microscopic and macroscopic electromagnetism in microscopic electromagnetism one deals with discrete point charges q i located at r n see figure 4. Text books leave much to be desired regarding visualization of wave propagation since they are not animated. James clerk maxwell derived a wave form of the electric and magnetic equations, thus uncovering the wavelike nature of electric and magnetic fields and their symmetry. It also gives out information about the first midterm exam. Parttime fifth semester electronics and communication engineering regulation 2009 download pdf file. Anomalous dispersion and resonant wave propagation in conducting media in the limit, there is a significant difference in the response of a dielectric medium to an electromagnetic wave, depending on whether the lowest resonant frequency is zero or nonzero. Because the speed of em waves predicted by the wave equation coincided with the measured speed of light, maxwell concluded that light itself is an em wave. Electromagnetic wave propagation is also affected by several other factors determined by its path from point to point. Upon discovery of the other propagation modes possible at medium wave.
In this section, we model a plane wave impinging on an airwater interface assuming the depth of water is infinite see. There is more information contained in maxwells equations than there is in the wave equation. Propagation and radiation of electromagnetic waves from oscil lating sources in a suddenly created plasma are studied in this investigation. If the wave is induced by and propagation from the voltage source battery, then it should take the vector path of the magnetic field created by the battery, instead of the circuit path. Using finite difference method, a propagating 1d wave is modeled. Other wave types cannot propagate through a vacuum and need a transmission. An oscillating charge in an lc circuit also produces em waves. Em wave propagation is achieved through guided structures such as transmission lines and waveguides or through space. Visualizing wave propagation file exchange matlab central. Destructive interference occurs when two waves are offset by a phase of m, or half a wavelength. While a rigorous analysis of an antenna is highly mathematical, often a simpli.
Point the fingers of your right hand in the direction of the. The vector r denotes the location in space where the. Electromagnetic wave propagation java tutorial olympus. The research reported in this document was made possible through support extended the massachusetts institute of tech nology, research laboratory of. Chapter maxwells equations and electromagnetic waves. For electromagnetic waves, propagation may occur in a vacuum as well as in a material medium.
If you drive the antenna with a dc source like a battery, then no em wave will be generated, because the battery only produces a. Ground wave propagation follows contour of the earth can propagate considerable distances frequencies up to 3 mhz example am radio 7. By successfully completing the nrtc, you indicate that you have met the objectives and have learned the. This is the threedimensional wave equation in vector form. Pdf on dec 6, 2019, jiahe shi and others published matlab simulation of electromagnetic waves propagation characteristics find, read and cite all the research you need on researchgate. Wave motion occurs when a disturbance at point a, at time to, is related to what happens at point b, at time t t0. An antenna or aerial is an electrical device which converts electric power into radio waves, and vice versa. Introduction to wave propagation of the many technical subjects that naval personnel are expected to know, probably the one least susceptible to change is the theory of wave propagation. For such a plane wave penetrating the fresh water, the total power loss is the sum of the transmission loss and propagation loss. Plane electromagnetic waves and wave propagation 7. Remember tracing light as lines through a curved lens and seeing whether the image was inverted or right side up and so on.
Abstractcharacteristics of electromagnetic wave propagation through a magnetized plasma slab with linear electron density profile is analysed. Candidates who are pursuing in class 12 are advised to revise the notes from this post. Suppose an electromagnetic plane wave with direction of propagation to be constructed, where is a. It is usually used with a radio transmitter or radio receiver. Groundwave propagation at frequencies up to about 3 mhz, the most important method of propagation is by ground waves which are vertically polarized. Wave propagation is any of the ways in which waves travel. Lecture notes 6 electromagnetic waves in matter electromagnetic wave propagation in linear media we now consider em wave propagation inside linear matter, but only in regions where there are no free charges free 0 andor free currents kfree 0 i. No theory is exhaustive, we make do, but relativistic physics is deeper than classical physics of course. Common to ptec 2353 antennas and wave propagation for b. The electromagnetic disturbance that results is propagated with the electronic e and magnetic b vectors vibrating perpendicularly to each other and also to the direction of propagation z. Electromagnetic wave propagation, radiation, and scattering. Please visit our blog for more videos in a listed way. Waveguide notes 2020 electromagnetic waves in free space. Dec 24, 2019 candidates who are pursuing in class 12 are advised to revise the notes from this post.
Study of electromagnetic wave propagation in active medium. Main result for a plane em wave 23 em wave in vacuum a wave propagating along z may be taken as 24 in a dielectric dispersion when. The behavior of these solutions is compared with those found elsewhere in the literature for the propagation of electromagnetic plane waves in a uniform active. This path can be a direct line of sight path or an overthehorizon path aided by refraction in the ionosphere. Maxwells equations govern all of electricity and magnetism, so it is no surprise. Electromagnetic wave propagation florida state university. Wave propagation is any of the ways in which waves travel with respect to the direction of the oscillation relative to the propagation direction, we can distinguish between longitudinal wave and transverse waves for electromagnetic waves, propagation may occur in a vacuum as well as in a material medium.
Wave equation maxwells equations contain the wave equation for electromagnetic waves. The visualization of em wave propagation as mutual induction of electric and magnetic fields isnt necessarily wrong its good classical physics, but it doesnt carry over to relativistic physics. For each of the waves use the righthand rule to determine the missing information. The figure shows the direction of propagation, direction of the electric field, andor the direction of the magnetic field for four electromagnetic waves.
Notes for electromagnetic waves chapter of class 12 physics. The events occurring in the transmission path between two stations that affect the communications between the stations. The propagation of an electromagnetic wave, which has been generated by a discharging capacitor or an oscillating molecular dipole, is illustrated by figure 1. This follows from the relativity fact that energy is equivalent. The wavefront of electromagnetic waves emitted from a point source such as a light bulb is a sphere. Visible light is a commonly studied form of electromagnetic radiation, and exhibits oscillating electric and magnetic fields whose amplitudes and directions are. The wave equation for light propagating in xdirection in vacuum may be written as where is the sinusoidally varying electric field at position x. You can also download the pdf version of text file used in this video. With the help of notes, candidates can plan their strategy for particular weaker section of the subject and study hard. Feb 03, 2017 please visit our blog for more videos in a listed way. Introduction an antenna is an electrical conductor or. Lower frequencies between 30 and 3,000 khz have the property of following the curvature of the earth. Ground wave propagation follows contour of the earth can propagate considerable distances frequencies up to 2 mhz example oam radio.
Electromagnetic plane wave of frequency and wave vector. In homogeneous, isotropic media, the oscillations of the two fields are perpendicular to each other and perpendicular to the direction of energy and wave propagation, forming a transverse wave. In the absence of free charge and current densities the maxwell equations are. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. If you drive the antenna with a dc source like a battery, then no em wave will be generated, because the battery only produces a dc current. Propagation of electromagnetic waves in anisotropic media. Propagation direction coherent light barrier with double slits constructive interference destructive. Since this has now become such a huge subject, the choice was to present a new approach we have developed largely by r.
Electromagnetic waves 1 light as waves in previous classes 15a, high school physics, you learned to think about light as rays. This lecture provides more details on the application of snells law at one single interface. One of the most methodical treatments of electromagnetic wave propagation, radiation, and scatteringincluding new applications and ideas. So, go ahead and check the important notes for class 12 physics electromagnetic waves and communication. Lineofsight propagation above 30 mhz neither ground nor sky wave propagation operates transmitting and receiving antennas must be within line of sight osatellite communication signal above 30 mhz not reflected by ionosphere oground communication antennas within effective line of site due to refraction. With respect to the direction of the oscillation relative to the propagation direction, we can distinguish between longitudinal wave and transverse waves. Electromagnetic wave propagation by professor david jenn ver1. A project to simulate the propagation of em waves in a bound media. He is a professor at iit bombay, this book gives a good journey of em waves the wave equation for electromagnetic waves follows from maxwells independent of r and t, we can write the six componen. Here we give a brief summary of the features of the theory that are needed to understand the formation, emission and propagation of electromagnetic waves. Substitute amperes law for a charge and currentfree region. May 30, 2017 one of the most methodical treatments of electromagnetic wave propagation, radiation, and scatteringincluding new applications and ideas. Wave propagation is a natural phenomenon that is important in many physical systems.
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