2002-2003 Catalog Descriptio

Engineering Sciences 151: Electromagnetic Communication. A study of electromagnetism which emphasizes concepts of central importance in computer and communication technology. Topics include: electromagnetic properties of matter; electromagnetic wave propagation through free-space and along waveguides; transmission line analysis; ray and beam optics; the eikonal and paraxial equations; characteristics of receiving and transmitting antennae. Applications illustrate critical factors which affect the design and limit the performance of communication systems.

Prerequisites: Familiarity with basic electromagnetism (Physics 15b), circuit analysis (Engineering Sciences 50 or 154) and Fourier analysis (Engineering Sciences 156, 125, or Applied Mathematics 105a).

Textbook:

• Yet to be decided

References:

• Telecommunications Engineering (3rd edition), J. Dunlop and D. G. Smith (Chapman & Hall, London 1994), ISBN 0-412-56270-7
• Fields and Waves in Communication Electronics (3rd Edition), Simon Ramo, John R. Whinnery, and Theodore Van Duzer (John Wiley and Sons, New York 1993), ISBN 0-471-58551-3.
• Transmission and Propagation of Electromagnetic Waves (2nd Edition), K. F. Sanders and G. A. L. Reed (Cambridge University Press, Cambridge, England, 1986), ISBN 0-521-31192-6.
• Antenna Theory: Analysis and Design, Constantine A. Balanis (Harper and Row, Publishers, New York 1982), ISBN 0-06-040458-2.
• Advanced Engineering Electromagnetics, Constantine A. Balanis (John Wiley and Sons, New York 1989), ISBN 0-471-62194-3.

Instructors:

R. Victor Jones, Robert L. Wallace Professor of Applied Physics
311 Cruft Laboratory
(617) 495-4447
e-mail: jones@deas.harvard.edu

Goals:

Engineering Science 151 is an intermediate level treatment of electromagnetic radiation. It provides a general introduction to the important physical concepts and mathematical methods used in treating all types of wave phenomena, but stresses electromagnetic signal propagation and issues of central importance in electrical engineering. As a core course in the Electrical Computer and Systems Engineering option of the Engineering Sciences concentration, it provides essential background and basic preparation for more advanced work in device physics, microwave and ultra-fast circuitry, antenna design, optics, optical communication and optoelectronics.

Prerequisites by Topic:

• An introductory year of college-level physics which includes experience in the use of vector calculus (Physics 15ab or, possibly, 11ab).
• A semester of linear circuit analysis (Engineering Sciences 154).
• Experience in Fourier analysis - Fourier series and integral transforms (Engineering Sciences 156 , 125 or Applied Mathematics 105a)

Topics (May be modified this year):

•  Signals and channels -- an overview of communication concepts: Shannon's model of communication processes; characteristics of auditory, video and data signals; information theory and measures of information content; analog and digital encoding of information -- AM, FM, ASK, FSK and all that; the sampling theorem; multiplexing formats. (2.5 lectures)
• Transmission line theory -- models, general methodology and applications: Fourier and phasor representations of time-dependent entities; the telegrapher equations; pulse propagation; steady-state, sinusoidal excitation; reflections and interference; Smith chart analysis. (5 lectures)
• Maxwell's equation -- a review of prerequisite material: operational definition of electromagnetic fields -- Lorentz force law; microscopic formulation of Maxwell's equations in both integral and differential forms; vector calculus -- div, grad, curl and all that, Poynting's theorem. (1 lecture)
• TEM waves -- electromagnetic wave propagation in vacuum and along simple waveguides: plane wave solutions to free space wave equation; wave impedance and polarization of plane waves; TEM waves guided by coaxial lines and similar structures. (2 lectures)
• Electromagnetic properties of materials: simple models of magnets, conductors and dielectric materials; macroscopic formulation of Maxwell's equations. (2 lectures)
• Electromagnetic wave propagation in materials: plane wave solutions in dielectric and conducting media; electromagnetic boundary and saltus conditions; reflection and refraction of plane waves at plane boundaries  -- Fresnel equations. (3 lectures)
• Planar waveguides: waves guided by parallel-plate and dielectric slab waveguides. (2 lectures)
• Ray or geometric optics (also called Gaussian optics): ray concept; Eikonal equations; analysis of optical systems in terms of ABCD matrices; GRIN optics. (2 lectures)
• Fiber optics: electromagnetic properties of glass; propagation characteristics of glass fiber; fiber optics communication systems. (1 lecture)
• Vector potentials: vector formulation of the inhomogeneous wave and Helmholtz equations. (1 lectures)
• Spherical waves and Gaussian beams. (2 lectures)
• Antennas: transmitting antennas -- analysis of radiation from known current distributions (viz. a Hertzian dipole, linear filamentary antennas and antenna arrays; radiation patterns, directivity and radiation resistance; receiving antennas - reciprocity theorem; aperture theory - diffraction and Fourier optics. (9 lectures)
• Real communication channels -- characteristics and limitations: overview of absorptive and dispersive characteristics various media; pulse propagation in dispersive media. (3 lectures)

Computer Usage:

Tools for mathematical analysis and computer simulations (mounted on computers in Cruft Laboratory) are utilized extensively throughout the course. In particular, the following software packages are used extensively.

• MATLABú (The MathWorks, Inc.): a technical computing environment for high-performance numeric computation and vizualization.
• SIMULINKú (The MathWorks, Inc.): an integrated signal analysis and processing simulation package based on MATLABúwhich is exceedingly valuable for studying signal characteristics and simulating communication operations.
• TLS: Transmission Line Simulator (Kinko Academic Courseware Exchange): a simple, but exceedingly valuable program which simulates and displays the real time response of transmission lines to transient and steady-state excitations.
• Electromagnetism (Stanford University, Kinko Academic Courseware Exchange): a suite of programs for simulating electromagnetic field patterns. In particular, Coulomb simulates the electric field patterns of static configurations of charge, Ampère simulates the magnetic field patterns of static configurations of current carriers, and Radiation simulates the time evolution of the electric field of an accelerating point charge.
• Optics Lab (Kinko Academic Courseware Exchange): a program which simulates the propagation of light rays through configurations of user-defined lenses and mirrors.
• Harvard Optical Benchand/or Ray Optics (Homegrown products): much better simulators of the light propagation through optical systems.

Laboratory Projects (May be modified this year):

A series of six experimental projects have been devised to demonstrate key communication concepts and measurement techniques.  Experimental studies include: modulation and demodulation of communication signals; wave propagation in lumped circuit element transmission lines; wave propagation through conducting media;  transmission characteristics of microwave circuit elements; light propagation in fiber optic systems; and radiation characteristics of antennas.

Other requirements:

Problem sets, computer labs, and laboratory projects will be assigned regularly and will be counted towards the course grade. There will be a mid-term examination and, of course, a final examination.  Both exams will cover material drawn from lectures, assigned readings, problem sets, computer labs, and laboratory assignments.