Electromagnetic Theory (IEEE Press Series on Electromagnetic Wave Theory)

649 Pages·2007·26.29 MB·English

by  Julius Adams Stratton

AN IEEE PRESS CLASSIC REISSUE
ELECTROMAGNETIC
THEORY
BY
JULIUS ADAMS STRATTON
Profeccor of Physics
Mu rsuchusetis Institute of Technology
IEEE Anfennas and Propagation Society, Sponsor
IEEE Press Series on Electromagnetic Wave Theory
Donald G. Dudley, Series Editor
IEEE
IEEE PRESS
@ CI*IL11*I*L
"IcIxII**IaL
WILEY -1NTERSCIENCE
A JOHN WILEY & SONS, INC., PUBLICATION
IEEE Press
445 Hoes Lane
Piscataway, NJ 08854
IEEE Press Editorial Board
Mohamed E. El-Hawary, Editor in Chie/
J. B. Anderson S. V. Kartalopoulos N. Schulz
R. J. Baker M. Montrose C. Singh
T. G. Croda M. S. Newman G. Zobrist
R.J. Herrick F. M. B. Pereira
Kenneth Moore, Director OfIEEE Book and Information Services (BIS)
Catherine Faduska, Senior Acquisitions Editor
Jeanne Audino, Project Editor
IEEE Antennas and Propagation Society, Sponsor
APS Liason to IEEE Press, Robert Mailloux
Copyright 0 2007 by the Institute of Electrical and Electronics Engineers, Inc. All rights reserved
Published by John Wiley & Sons, Inc., Hoboken, New Jersey.
No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form
or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as
permitted under Section 107 or 108 of the 1976 United States Copyright Act, without either the prior
written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to
the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, [phone], fax
[phone], or on the web at www.copyright.com. Requests to the Publisher for permission should
be addressed to the Permissions Department, John Wiley & Sons, Inc., 11 1 River Street, Hoboken, NJ
07030, (201) 748-601 I, fax [phone], or online at http://www.wiley.com/go/permission.
Limit of LiabilityiDisclaimer of Warranty: While the publisher and author have used their best efforts in
preparing this book, they make no representations or warranties with respect to the accuracy or
completeness of the contents of this book and specifically disclaim any implied warranties of
merchantability or fitness for a particular purpose. No warranty may be created or extended by sales
representatives or written sales materials. The advice and strategies contained herein may not be
suitable for your situation. You should consult with a professional where appropriate. Neither the
publisher nor author shall be liable for any loss of profit or any other commercial damages, including
but not limited to special, incidental, consequential, or other damages.
For general information on our other products and services or for technical support, please contact our
Customer Care Department within the United States at [phone], outside the United States at
(3 17) 572-3993 or fax [phone].
Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may
not be available in electronic format. For information about Wiley products, visit our web site at
www.wiley.com.
Library of Congress Cataloging-in-Publication Data is available.
ISBN-I3 978-0-470-13153-4
ISBN-I0 0-470-13153-5
Printed in the United States of America.
I 0 9 8 7 6 5 4 3 2 1
FOREWORD TO THE REISSUED EDITION
The purpose of the IEEE Press Series on Electromagnetic Wave Theory is to pub-
lish books of long-term archival significance in electromagnetics. Included are new
titles as well as reissues and revisions of recognized classics. The book Electromag-
netic Theory, by J. A. Stratton is one such classic.
Originally published in 194 I, Stratton’s book has formed an integral part of the
electromagnetic education of both physics and electrical engineering graduate stu-
dents for over sixty years. In addition, virtually every electromagnetic researcher I
know has a copy in hidher library. Unfortunately, the book is out of print. It is our
purpose to rectify this situation.
When I consult my copy of this classic book, I never cease to be amazed at its
timeliness. The equivalence principle is strongly rooted in the Stratton-Chu inver-
sion of the vector wave equations, contained on pages 464-470. The Hansen vectors
are introduced and exploited in Chapter VII. The Sommerfeld problem is discussed
in Section 9.28. Natural modes along circular cylinders embedded in a lossy medi-
um are developed in Section 9.15. I could go on and on. Suffice it to say that the de-
velopment of the theory and the inclusion of examples remain of current interest to-
day.
Professor Stratton had an amazing career, culminating with his succession to the
presidency of the Massachusetts Institute of Technology (MIT). Another former
president, Professor Paul E. Gray, has kindly agreed to write an introduction to this
reissued edition, highlighting Stratton’s achievements. I am indebted to Professor
Stratton’s surviving spouse, Kay Stratton, who kindly agreed to our reissue plans
and then assisted in making the project possible. In addition, I should like to thank
Carol Fleishauer, Associate Director for Collection Services of the MIT Libraries
who made available from their archives a pristine copy of the book for our use in
the reissue.
Over the past twelve years, I have received many requests worldwide to reissue
this book. It is with great pleasure that I welcome it to the IEEE Press Series on
Electromagnetic Wave Theory.
DONALDG .D UDLEY
University of Arizona
V
Professor Julius Adams Stratton. Courtesy MIT Museum.
INTRODUCTION
Julius Adams Stratton served the Massachusetts Institute of Technology, The Radi-
ation Laboratory at MIT, the Federal Government, the National Academies of Sci-
ence and Engineering and the Ford Foundation during his long and productive life.
His work at MIT, both as a member of the faculty, and as provost and subsequently
president, was important in the development of both research and education during
intervals of rapid growth and change in the Institute.
Stratton was born on May 18, 1901 in Seattle, Washington. His father, Julius A.
Stratton, was an attorney who founded a law firm well known and respected
throughout the Northwest. He also served as a judge. His mother, Laura Adams
Stratton, was an accomplished pianist. Following his father’s retirement, the family
moved to Germany in 1906 where Stratton attended school through age nine and
developed fluency in the German language. The family returned to Seattle in 1910
where he completed his public school education.
Stratton came to MIT, with which he was associated for 74 years, as the result of
an accident at sea and the advice of a student friend. He had an early interest in find-
ing out how things worked and in building things, particularly those that involved
electricity. In high school he became very interested in radio in those early days of
spark-gap transmitters and galena crystal detectors. These interests, coupled with
the shutdown of amateur radio operations during World War I and the desire to
serve the nation, led him to study and qualify as a commercial radio operator-sec-
ond grade-and to sign on during summer vacations as a shipboard radio operator.
Stratton had been admitted to Stanford for matriculation in September 1919, and
signed on for that summer as radio operator on the SS Western Glen out of Seattle
for a trip to Japan and Manchuria. The ship encountered a typhoon near Kobe,
Japan and participated in the rescue of another American ship in distress. Also, it
experienced an engine failure at the start of the return voyage that required a return
to port in Japan. These accidents made him late in returning to the US-too late to
enroll at Stanford that year. As an alternative, he succeeded in enrolling late at the
University of Washington in Seattle. During that year, in which he pursued his in-
terests in electricity and mathematics, a conversation with a UW classmate persuad-
ed him to apply for transfer to MIT, where he was admitted in 1920. He traveled to
the Institute as a radio operator-this time first grade--on the SS Eastern Pilot via
Balboa, Panama and New York City, arriving in August 1920, a week before the
start of classes.
At MIT Stratton enrolled in the Electrical Communications; Telegraph, Tele-
phone and Radio option of the Department of Electrical Engineering, which he de-
scribed in a letter home as “. . . far more interesting than that of ordinary dynamo-
electric machinery. Line telegraphy and telephony involve some of the most
complex mathematics known.” He received his SB Degree in June 1923 with a the-
sis entitled “The Absolute Calibration of Wavemeters.” The equipment he devel-
oped generated harmonics up to 30 megahertz from a one kilohertz tuning fork.
During his senior year, Stratton determined to continue his studies in Europe. He
vii
...
Vlll INTRODliC‘TlON
traveled to Paris via Cherbourg (this time as a passenger), with the dual goals of
continuing his engineering studies and becoming fluent in the French language.
During the ’23-‘24 year he traveled to and studied in Nancy, Grenoble, Toulouse
and Italy returning to the US in August 1924.
From September 1924 through June 1926 he was, as a research assistant in com-
munications, enrolled at MIT in a master’s degree program, graduating with a thesis
entitled “A High Frequency Bridge.”
Upon completion of his graduate studies at MIT Stratton received a traveling fel-
lowship that enabled him to again return to Europe, where many universities
seethed with excitement about quantum theory and atomic structure. He enrolled
for a doctor of science degree at the Eidgenossische Technische Hochschule (ETH)
in Zurich, Switzerland where he studied with Debye, graduating in March 1928
with a thesis entitled “Streuungskoeffzient von Wasserstoft nach der Wellenme-
chanic” (The Scattering Coefficient of Hydrogen According to Wave Mechanics).
He was invited to return to MIT as an assistant professor in electrical engineering-
a modern physicist embedded in the engineering department. This appointment
marked the beginning of 38 years of continuous active association with the Insti-
tute.
Stratton’s desire to see the world was obviously very strong. During the sum-
mers he traveled to Africa, the Yukon and to Ecuador. His interest in other cultures
and other nations was deep.
On June 14, 1935, in Saint Paul’s Chapel at Ivy Depot, Virginia, Julius Adams
Stratton and Catherine Nelson Coffman were married. From this fortunate marriage
came three daughters: Catherine, Cary, and Laura. Their mother, known to all as
Kay, is active in the MIT community, as a founding member of the Council for the
Arts and as the guiding force behind two annual panel discussions: one each fall in
a topic of current interest; and one each spring on some aspect of ageing gracefully.
His experiences at the ETH changed Stratton’s career interests and further devel-
oped his passion for mathematics and physics. As he put it “In the years 1923-1924
I was thinking of a doctorate in literature or philosophy. This was to be the subject:
The Influence of Science on 19th Century French Literature. I decided to go into
pure physics. The years 1925 through 1928 changed my mind.” In 1930 his ap-
pointment was moved to the Department of Physics.
Karl Taylor Compton, the newly arrived president, set out to strengthen the sci-
ences at MIT generally, and to give greater emphasis to modern physics. Stratton
became part of that transformation. He was promoted to professor in 1941, the same
year this book, Electromugnetic Theory, was published by McGraw Hill. His book,
although long out of print, is still widely used and referenced by 21st century writ-
ers. The decision of the IEEE to republish it as part of their series of electrical engi-
neering classics will be much appreciated by engineers
Much of his research in the 1930s was done at the Round Hill Experiment Sta-
tion in South Dartmouth, Massachusetts. Stratton’s research there involved the
propagation of very short radio waves and light through rain and fog. He also stud-
ied the possibility of using intense electromagnetic radiation to disperse fog, and
made measurements of the field of an antenna over the open sea, employing the
INTRODUC’TION ix
Mqjlower, a dirigible loaned to him by the Goodyear Zeppelin Company. He pre-
pared and published, through the National Academy of Sciences, tables of spher-
oidal functions-solutions of differential equations that arose in his studies of an-
tennas. Between 1927 and 1942 Stratton published eleven technical papers in
refereed journals.
The German invasion of Poland in 1939 changed everything for Stratton. Prior
to the start of the war, British scientists employed high-frequency radio waves (ca
100 megahertz) as an early form of radar by exploiting reflections from aircraft.
They realized that higher frequencies would both enable much smaller antennas and
yield greater precision in target location, but were unable to generate radiation of
sufficient intensity at frequencies in the gigahertz range. Their invention of the mi-
crowave magnetron, in the months before the war started, enabled the creation of
radar systems that would be of much greater effectiveness in the war. Unsure that
they would be able to pursue the essential development in Britain under wartime
conditions, they sent the Tizard Mission with the magnetron and its developers to
the US, where American engineers and scientists could develop militarily useful
microwave radar systems quickly.
The Federal government established the Radiation Laboratory at MIT in October
1940 and Stratton was one of many who took on the tasks of making microwave
radar useful to the military on land and on sea as well as in the air. He was a natural
for this work given his understanding of electromagnetic radiation and the applica-
tions of Maxwell’s equations. He was appointed in November 1940 as a volunteer
consultant to the Microwave Section of Division D of the National Defense Re-
search Council, and seconded by MIT to the Rad Lab (as it was universally called).
In August 1942 Stratton was appointed Expert Consultant to the Secretary of
War, Henry G. Stimson. He served in that capacity until December 1945. In this
role he made frequent visits to the theaters of war. In October 1942, as a member of
a committee investigating communication problems in the North Atlantic he trav-
eled by air to England with extended stops in Presque Isle, Labrador, Greenland and
Iceland. In 1943, soon after the Allied invasion of North Africa, he traveled to Al-
giers, Tunis, Italy, and London to assess radar utility and communications effective-
ness.
Robert Buderi wrote in The Invention that Changed the World (Touchstone,
1997): “The Atomic Bomb only ended the war. Radar won it.” Stratton was a very
significant part of that critically important development.
In August 1945 the Office of Scientific Research and Development, that had
overseen all of the laboratories created to aid the war effort, was shut down, and the
Radiation Laboratory was told to wind up its affairs. On January 1, 1946 Stratton
took over administration of the Division of Basic Research of the Lab, which had
been created in August 1945 following the surrender of the Japanese government.
At the suggestion of John Slater, head of the physics department, he named the Di-
vision the MIT Research Laboratory of Electronics (RLE).
Research support in the early days of RLE came from the Department of De-
fense through a multi-services contract, much of it in the form of a block grant at
the level of $600,000 per year. RLE was “responsible for extending the useful range
of the electromagnetic spectnim . . . to shorter wavelengths, approaching ultimately
that of infra-red.”
Title to the temporary buildings in the heart of the MIT campus that housed the
Rad Lab and to all the equipment contained therein was transferred to RLE in July
1946. The largest of those “temporary buildings” became “Building 20.” Until its
demise in 1998 at age 55, is was cherished prime research space at the Institute.
Stratton, as the founding director, led RLE during its formative years as the na-
tion’s first university-based interdepartmental research laboratory. Its history, now
spanning more than sixty years of scientific and engineering accomplishments, has
its origins in Stratton’s vision and leadership.
In 1949 James Rhyne Killian, Jr. succeeded Karl Taylor Compton as president of
the Institute, and Killian appointed Stratton as the Institute’s first Provost.
The fifties and sixties were years of extraordinary growth at MIT. Vannevar
Bush’s landmark report, Science, the Endless Frontier led to the creation of the Na-
tional Science Foundation and the National Institutes of Health. Cold War tensions,
much increased in 1957 by the Soviet’s launch of Sputnik, caused enrollments in
engineering and science to grow rapidly throughout this period. The Federal Gov-
ernment greatly expanded financial support for research and for students in the
fields of science and engineering. Charles Stark Draper’s Instrumentation Laborato-
ry (later to become the independent Draper Laboratory) expanded greatly to add the
Apollo mission to its development of inertial navigation systems for the military
services. The compound annual growth rate of sponsored research at the Institute
was in double digits until 1969.
Stratton was primarily responsible for management of the physical and intellec-
tual growth of MIT in these decades and for the thoughtful development and imple-
mentation of necessary structures, policies and procedures that became the founda-
tions of, and the models for, the modem MIT. During his time as provost, two new
schools were created, the School of Humanities and Social Sciences in 1950 and the
Sloan School of Management in 1952.
In 1957 Killian was called to Washington to serve as President Eisenhower’s
Science Advisor, and Stratton, who had been appointed Chancellor in 1956, became
acting president and an ex oficio member of the governing board. In 1958 he was
elected eleventh president of the Institute. His presidency was a time of physical ex-
pansion for MIT. New buildings for Chemistry, Earth Sciences, Biology and the
Center for Materials Science and Engineering filled former parking lots. Mc-
Cormick Hall, the first dormitory for undergraduate women, was completed in
1965. This was the crucial first step in increasing the number of women at MIT,
who now comprise 45% of the undergraduate student body. Stratton was liked and
respected by MIT students, who suggested that the new student center, completed
in 1966 be named for him.
As founding director of RLE, as provost, and as chancellor and president, Jay
Stratton deserves, along with Compton and Killian, a large share of credit for the
transformation of MIT from the premier school of engineering to a modern research
university.
Stratton was elected a member of the National Academy of Sciences (NAS) in
1950. Although there was a section of the NAS for distinguished engineers, there
INTRODUL‘T/ON xi
were very few such members. The national engineering societies affiliated with the
Engineers’ Joint Council suggested in 1963 that a new organization to be called the
National Academy of Engineering (NAE) be created. Stratton, who was at the time
a member of the NAS Council, chaired a committee that worked through the com-
plex issues of the idea and that led to the creation in 1964 of thc NAE as an affiliate
of the NAS. The two academies, joined some years later by the Institute of Medi-
cine, comprise the premier organization for responding to questions or requests for
studies that come from the Federal government. Stratton’s clarity of vision and per-
suasiveness were very important in shaping the expansion of the enterprise, which
is now commonly referred to simply as “The National Academies.”
Following his retirement from MIT in 1966, Stratton accepted appointment as
Chairman of the Board of the Ford Foundation in New York City. At that time the
Ford Foundation was the nation’s largest grant-making charitable foundation. Strat-
ton’s interest in MIT affairs continucd during his time in New York. Hc remained a
member of the Institute’s governing board and served on several of its committees.
During his years at the Ford Foundation Stratton accepted presidential appoint-
ment in 1967 as Chairman of the Committee on Marine Sciences, Engineering and
Resources (COMSER). The charge to the committee was, in part, to recommend
“National Policy to develop, encourage and maintain a coordinated, comprchen-
sive, and long range program in marine science for the benefit of mankind . . . ex-
panding scientific knowledge of the marine environment and of developing an
ocean engineering capability to accelerate exploration and development of marine
resources. . . .”
COMSER’s report: Our Nation and the Seu. A Plan for Nutional Action was pre-
sented to a different president and published two years later in January 1969. An
outcome of the study was the creation of NOAA, the National Oceanic and Atmos-
pheric Agency.
Stratton returned to MIT in 1971 full time when his term as chairman of the Ford
Foundation ended. His affection and concern for the university that was integral to
his professional life for more than 50 years was undiminished by his years in New
York, and his renewed engagement in the life of MIT was immediately evident.
Jay Stratton died on June 22, 1994. During the last twenty years of his life, he
had the opportunity to see up-close the transformation from premier engineering
school to important world-class research university that he, together with Compton
and Killian, had commenced sixty years earlier.
In the preface to Electromugnetic Theory, Stratton noted that his wife Catherine
had assisted him in its preparation by proofreading the galleys with him. In the
preparation of this edition she has worked enthusiastically and closely with the
IEEE to enable the book’s republication.
PAULE . GRAY
Professor of Electrical Engineering
President Emeritus
MIT
October 2006
PREFACE
The pattern set nearly 70 years ago by Maxwell’s Treatise on Electric-
ity and Magnetism has had a dominant influence on almost every subse-
quent English and American text, persisting to the present day. The
Treatise was undertaken with the intention of presenting a connected
account of the entire known body of electric and magnetic phenomena
from the single point of view of Faraday. Thus it contained little or
no mention of the hypotheses put forward on the Continent in earlier
years by Riemann, Weber, Kirchhoff, Helmholtz, and others. It is
by no means clear that the complete abandonment of these older theories
was fortunate for the later development of physics. So far as the
purpose of the Treatise was to disseminate the ideas of Faraday, it was
undoubtedly fulfilled; as an exposition of the author’s own contributions,
it proved less successful. By and large, the theories and doctrines
peculiar to Maxwell-the concept of displacement current, the identity
of light and electromagnetic vibrations-appeared there in scarcely
greater completeness and perhaps in a less attractive form than in the
original memoirs. We find that all of the first volume and a large part
of the second deal with the stationary state. In fact only a dozen pages
are devoted to the general equations of the electromagnetic field, 18 to
the propagation of plane waves and the electromagnetic theory of light,
and a score more to magnetooptics, all out of a total of 1,000. The
mathematical completeness of potential theory and the practical utility of
circuit theory have influenced English and American writers in very
nearly the same proportion since that day. Only the original and
solitary genius of Heaviside succeeded in breaking away from this course.
For an exploration of the fundamental content of Maxwell’s equations
one must turn again to the Continent. There the work of Hertz, Poin-
car6, Lorentz, Abraham, and Sommerfeld, together with their associates
and successors, has led to a vastly deeper understanding of physical
phenomena and to industrial developments of tremendous proportions.
The present volume attempts a more adequate treatment of variable
electromagnetic fields and the theory of wave propagation. Some atten-
tion is given to the stationary state, but for the purpose of introducing
fundamental concepts under simple conditions, and always with a view
to later application in the general case. The reader must possess a
general knowledge of electricity and magnetism such as may be acquired
from an elementary course based on the experimental laws of Coulomb,
...
Xlll