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Title: Fundamentals of Electromagnetics for Teaching and Learning: A Two-Week Intensive Course for Faculty in Electrical-, Electronics-, Communication-, and Computer- Related Engineering Departments in Engineering Colleges in India


1
Fundamentals of Electromagneticsfor Teaching and
LearningA Two-Week Intensive Course for Faculty
inElectrical-, Electronics-, Communication-, and
Computer- Related Engineering Departments in
Engineering Colleges in India
  • by
  • Nannapaneni Narayana Rao
  • Edward C. Jordan Professor Emeritus
  • of Electrical and Computer Engineering
  • University of Illinois at Urbana-Champaign, USA
  • Distinguished Amrita Professor of Engineering
  • Amrita Vishwa Vidyapeetham, India

2
Program for Hyderabad Area and Andhra Pradesh
FacultySponsored by IEEE Hyderabad Section, IETE
Hyderabad Center, and Vasavi College of
EngineeringIETE Conference Hall, Osmania
University CampusHyderabad, Andhra PradeshJune
3 June 11, 2009 Workshop for Master Trainer
Faculty Sponsored byIUCEE (Indo-US Coalition for
Engineering Education)Infosys Campus, Mysore,
KarnatakaJune 22 July 3, 2009
3
Introductory PresentationPart 2
4
Terminology
  • Because I will be using the term electrical and
    computer engineering it is of interest to
    elaborate upon this terminology. In engineering
    departments in the United States educational
    institutions, electrical and computer engineering
    is generally one academic department, although
    not in all institutions. The name, ECEDHA,
    Electrical and Computer Engineering Department
    Heads Association, reflects this situation. In
    the College of Engineering at the University of
    Illinois at Urbana-Champaign (UIUC), the
    Department of Electrical and Computer Engineering
    (ECE) offers two undergraduate programs leading
    to the Bachelor of Science degrees Electrical
    Engineering and Computer Engineering.

5
The Scope of Electrical Engineering
  • A list of the twenty greatest engineering
    achievements of the twentieth century compiled by
    the National Academy of Engineering includes ten
    achievements primarily related to the field of
    electrical engineering electrification,
    electronics, radio and television, computers,
    telephone, internet, imaging, household
    appliances, health technologies, and laser and
    fiber optics. The remaining achievements in the
    list - automobile, airplane, water supply and
    distribution, agricultural mechanization, air
    conditioning and refrigeration, highways,
    spacecraft, petroleum/petrochemical technologies,
    nuclear technologies, and high-performance
    materials - also require knowledge of electrical
    engineering to differing degrees. In the
    twenty-first century the discipline of electrical
    engineering continues to be one of the primary
    drivers of change and progress in technology and
    standards of living around the globe.

6
NAEs List of Greatest Engineering Achievements
of the 20th Century
  • Electrification
  • Automobile
  • Airplane
  • Water Supply Distribution
  • Electronics
  • Radio Television
  • Agricultural Mechanization
  • Computers
  • Telephone
  • Air Conditioning Refrigeration
  • Highways
  • Spacecraft
  • Internet
  • Imaging
  • Household Appliances
  • Health Technologies
  • Petroleum/Petrochemical Technologies
  • Laser Fiber Optics
  • Nuclear Technologies
  • High-Performance Materials

Red indicates areas where ECE at UIUC has had
influence.
7
The Scope of Computer Engineering
  • Computer engineering is a discipline that
    applies principles of physics and mathematics to
    the design, implementation, and analysis of
    computer and communication systems. The
    discipline is broad, spanning topics as diverse
    as radio communications, coding and encryption,
    computer architecture, testing and analysis of
    computer and communication systems, vision, and
    robotics. A defining characteristic of the
    discipline is its grounding in physical aspects
    of computer and communication systems. Computer
    engineering concerns itself with development of
    devices that exploit physical phenomena to store
    and process information, with the design of
    hardware that incorporates such devices, and with
    software that takes advantage of this hardware's
    characteristics. It addresses problems in design,
    testing, and evaluation of system properties,
    such as reliability, and security. It is an
    exciting area to work in, one that has immediate
    impact on the technology that shapes society
    today.

8
The Illinois Curriculum in Electrical Engineering
  • For the electrical engineering program at
    Illinois, the core curriculum focuses on
    fundamental electrical engineering knowledge
    circuits, systems, electromagnetics, solid state
    electronics, computer engineering, and design. A
    rich set of elective courses permits students to
    select from collections of courses in seven areas
    of electrical and computer engineering
    bioengineering, acoustics, and magnetic resonance
    engineering circuits and signal processing
    communication and control computer engineering
    electromagnetics, optics, and remote sensing
    microelectronics and quantum electronics power
    and energy systems.

9
The Illinois Curriculum in Computer Engineering
  • For the computer engineering program, the core
    curriculum focuses on fundamental computer
    engineering knowledge circuits, systems,
    electromagnetics, computer engineering, solid
    state electronics, and computer science. A rich
    set of elective courses permits students to
    concentrate in any sub-discipline of computer
    engineering including computer systems
    electronic circuits networks engineering
    applications software, languages, and theory
    and algorithms and mathematical tools.

10
Electromagnetics is all around us!
  • In simple terms, every time we turn a switch on
    for electrical power or for an electronic
    equipment, every time we press a key on our
    computer key board or on our cell phone, or every
    time we perform a similar action involving an
    everyday electrical device, electromagnetics
    comes into play.

11
Some modern applications of EM (Courtesy of Weng
C. Chew)
12
Fundamental to the Study of ECE
  • It is the foundation for the technologies of
    electrical and computer engineering, spanning the
    entire electromagnetic spectrum, from dc to
    light. As such, in the context of engineering
    education, it is fundamental to the study of
    electrical and computer engineering.

13
Foundation for the technologies of electrical and
computer engineering
14
Fundamental to the Study of ECE
In 1963, the American Institute of Electrical
Engineers (AIEE) and the Institute of Radio
Engineers (IRE) were merged into the Institute of
Electrical and Electronics Engineers (IEEE), a
global nonprofit organization with over 375,000
members, and the world's leading professional
association for the advancement of technology.
The IEEE logo or badge is a merger of the badges
of the two parent organizations. It contains a
vertical arrow surrounded by a circular arrow,
within a kite-shaped border. No letters clutter
the badge because a badge without letters can be
read in any language. The AIEE badge had the kite
shape which was meant to symbolize the kite from
Benjamin Franklins famous kite experiment to
study electricity. The IRE badge had the two
arrows that symbolize the right hand rule of
electromagnetism.
15
Fundamental to the Study of ECE
Alternatively, the vertical arrow can be thought
of as representing one of the two fields,
electric or magnetic, and the circular arrow
surrounding it representing the second field,
produced by it, so that together they represent
an electromagnetic field.
16
Fundamental to the Study of ECE
Whether this logo of IEEE was intended to be a
recognition of the fact that electromagnetics is
fundamental to all of electrical and computer
engineering, it is a fact that all electrical
phenomena are governed by the laws of
electromagnetics, and hence, the study of
electromagnetics is essential to all branches of
electrical and computer engineering, and
indirectly impacts many other branches.
17
EM is so fundamental that even Mac Circuits Van
Valkenburg was caught having fun communicating
the RH Rule to Robert Communications Lucky!
Wonderful picture!
18
An amusing incident
  • One of the earliest postwar programs to be
    established at UIUC was a program in radio
    direction finding (RDF). It was intended as a
    basic research program, sponsored by the Office
    of Naval Research. When the sponsor was asked by
    the research supervisor, Edward Jordan, what
    facets of the field might be of particular
    interest, the answer received was Look, you
    know Maxwells equations, the Russians know
    Maxwells equations you take it from there.
    Jordan was amused that it would be difficult to
    get more basic than that.

19
Wullenweber Array at Bondville Road Field Station
of the RDF Laboratory
  • Used in Radio Direction Finding Laboratory
  • In operation 1955-1980
  • Used 120 antennas and was 1000 ft in diameter
  • Operated in frequency range of 4-16 MHz

20
Wullenweber array of the RDF Laboratory (1955
1980)
21
Discovering Wullenweber while riding the
Pineapple Express at the Dole Plantation on the
island of Oahu, Hawaii, with family on June 4,
2005, as a reminder
22
Wullenweber and Bananas (My favorite slide)
23
So, what is Electromagnetics?
By the very nature of the word, electromagnetics
implies having to do with a phenomenon involving
both electric and magnetic fields and furthermore
coupled. This is indeed the case when the
situation is dynamic, that is, time-varying,
because time-varying electric and magnetic fields
are interdependent, with one field producing the
other.
24
What is Electromagnetics?
In other words, a time-varying electric field or
a time-varying magnetic field cannot exist alone
the two fields coexist in time and space, with
the space-variation of one field governed by the
time-variation of the second field. This is the
essence of Faradays law and Amperes circuital
law, the first two of the four Maxwells
equations resulting in wave propagation.
25
About Electromagnetics (Continued)
Only when the fields are not changing with time,
that is, for the static case, they are
independent a static electric field or a static
magnetic field can exist alone, with the
exception of one case in which there is a one-way
coupling, electric field resulting in magnetic
field, but not the other way.
26
About Electromagnetics (Continued)
Thus, in the entire frequency spectrum, except
for dc, all electrical phenomena are, in the
strictest sense, governed by interdependent
electric and magnetic fields, or electromagnetic
fields.
27
Quasistatic Approximation
However, at low frequencies, an approximation,
known as the quasistatic approximation, can be
made in which the time-varying fields in a
physical structure are approximated to have the
same spatial variations as the static fields in
the structure obtained by setting the source
frequency equal to zero.
28
Quasistatic Approximation (Continued)
Thus, although the actual situation in the
structure is one of electromagnetic wave nature,
it is approximated by a dynamic but not wavelike
nature. As the frequency becomes higher and
higher, this approximation violates the actual
situation more and more, and it becomes
increasingly necessary to consider the wave
solution.
29
Statics f 0 dc Dynamics
No restriction complete Maxwells equations
Electromagnetic waves Quasistatics
Low-frequency extension of statics, or
low-frequency approximation of
dynamics
30
Maxwells Equations are elegant and beautiful.
As profound as they are, they are actually quite
simple to explain and understand.
31
Maxwells Equations
d


E
d
l


B
d
S
ò
ò
dt
S
C
Charge density
Electric field intensity
Magnetic flux density
d




B
d
S

0
ò
ò
ò
ò
H
d
l

J
d
S

D
d
S
dt
S
S
C
S
Current density
Magnetic field intensity
Displacement flux density
32
Faradays Law, the first EMantra
Electromotive Force (emf) or voltage around C
Negative of the time rate of increase of
the magnetic flux crossing S bounded by C.
33
Voltage around C, also known as electromotive
force (emf) around C (but not really a force),
Magnetic flux crossing S,
Time rate of decrease of magnetic flux crossing
S,
34
Amperes Circuital Law, the second EMantra
Magnetomotive force (mmf) around C Current due
to flow of charges crossing S bounded by C
Time rate of increase of electric (or
displacement) flux crossing S
35
Magnetomotive force (only by analogy with
electromotive force),
Current due to flow of charges crossing S,
Displacement flux, or electric flux, crossing S,
36
Time rate of increase of displacement flux
crossing S, or, displacement current crossing S,
37
  • Gauss Law for the Electric Field, the third
    EMantra
  • Displacement flux emanating from a closed
    surface S
  • charge contained in the volume V bounded by S
  •  charge enclosed by S

r
38
Gauss Law for the Magnetic Field, the fourth
EMantra
  • Magnetic flux emanating from a closed
    surface S  0.

39
Out of the four EMantras, only the first two,
Faradays and Amperes circuital laws are
independent. The fourth Mantra, Gauss law for
the magnetic field, follows from Faradays law,
and the third Mantra, Gauss law for the electric
field, follows from Amperes circuital law, with
the aid of an auxiliary equation, the law of
conservation of charge.
40
Law of Conservation of Charge, an auxiliary
EMantra
r(t)
  • Current due to flow of charges emanating from a
    closed surface S
  • Time rate of decrease of charge enclosed by S.

41
Maxwells Equations in Differential Form and the
Continuity Equation
Faradays Law
Amperes Circuital Law
Gauss Law for the Electric Field
Gauss Law for the Magnetic Field
Continuity Equation
42
Time derivatives of the components of B
Lateral space derivatives of the components of E
Charge density
43
The Mahatmyam (Greatness) of Maxwells Equations
44
The Mahatmyam (Greatness) of Maxwells Equations
Amperes Circuital Law
Law of Conservation of Charge
Faradays Law
?
Gauss Law for E
45
The Mahatmyam (Greatness) of Maxwells Equations
Thus, Faraday's law says that a time-varying
magnetic field gives rise to an electric field,
the space-variation of which is related to the
time-variation of the magnetic field.  Ampere's
circuital law tells us that a time-varying
electric field produces a magnetic field, the
space variation of which is related to the
time-variation of the electric field.  Thus, if
one time-varying field is generated, it produces
the second one, which in turn gives rise to the
first one, and so on, which is the phenomenon of
electromagnetic wave propagation, characterized
by time delay of propagation of signals. In
addition, Amperes circuital law tells us that an
electric current produces a magnetic field, so
that a time-varying current source results in a
time-varying magnetic field, beginning the
process of one field generating the second.
46
Hertzian Dipole
47
Radiation from Hertzian Dipole
48
Hertzian dipole and radiation pattern on the
covers of the U.S. and Indian Editions of
Fundamentals of Electromagnetics
49
The Contribution of Maxwell
You will have noted that none of the four
equations are named after Maxwell. So, the
question arises as to why they are known as
Maxwells equations. It is because of a purely
mathematical contribution of Maxwell. This
mathematical contribution is the second term on
the right side of Amperes circuital law. Prior
to that, Amperes circuital law consisted of only
the first term on the right side.
50
The Contribution of Maxwell
Without the second term on the right side of
Amperes circuital law, the loop is not complete
and hence there is no interdependence of
time-varying electric and magnetic fields and no
EM waves!
51
Unifying Electricity and Magnetism
Thus, the purely mathematical contribution of
Maxwell in 1864 unified electricity and magnetism
and predicted the generation of EM waves owing to
the interdependence of time-varying electric and
magnetic fields. Only 23 years later in 1887,
eight years after his death in 1879, the theory
was proved correct by the experimental discovery
of EM waves by Heinrich Hertz.
52
  • Parallel with Principles from Upanishads
  • In fact, Maxwells Equations are as fundamental
    to the science of all electrical phenomena and
    hence to modern living as the Guiding Principles,
  • from the Taittriyopanishad are to spirituality.

53
The Guiding Principles from Upanishads
54
The Guiding Equations of Electromagnetics
55
Maxwells Equations parallel to the Principles in
Upanishads! Isnt it fascinating!
56
So, why are these poor little guys so perplexed
at the sight of Maxwells Equations?
57
Why is the teaching and learning of EM so
dreaded, as implied by this mnemonic?
HOW I WANT A DRINK, 3. 1 4 1 5
ALCOHOLIC, OF COURSE, 9 2
6 AFTER THE HEAVY LECTURES 5
3 5 8 INVOLVING ELECTRO-MAGNETICS!
9 7 9
58
Incomplete list of reasons given
  • Abstract (not practical ideal theoretical hard
    to understand difficult abstruse)
  • Mathematical complexity
  • Vector notation
  • Curl, divergence, and gradient
  • Highly conceptual

59
The approach to the teaching of electromagnetics
While these might be valid reasons to differing
degrees for different people, depending on their
background preparations, let us look at the
teaching of EM.
60
The approach to the teaching of electromagnetics
Historically, the development of major
technologies based on Maxwells equations
occurred in the sequence of electrically and
magnetically based technologies (electromechanics
and electrical power) in the nineteenth century
electronics hardware and software in the
twentieth century and photonics technologies,
entering into the twenty-first century.
61
Progression of technologies based on Maxwells
Equations
62
The approach to the teaching of electromagnetics
The teaching of electromagnetics evolved
following this sequence, that is, beginning with
a course on electrostatics, magnetostatics,
energy and forces, and in some cases quasistatic
fields, followed by Maxwells equations for
time-varying fields and an introduction to
electromagnetic waves. This course was then
followed by one or more courses on transmission
lines, electromagnetic waves, waveguides and
antennas.
63
The historical, or, inductive approach
The teaching of the introductory course in this
manner is known as the inductive approach, that
is, an approach consisting of developing general
principles from particular facts, which in this
case was developing complete set of Maxwells
equations from the particular laws of static
fields. Since generally much time is taken up
for the coverage of static fields before getting
to the complete set of Maxwells equations, the
time is cut short (and in some cases not
available) for the more interesting and useful
material, centered on electromagnetic waves. This
is the principal drawback of the traditional,
inductive, approach, which is unnecessarily
aggravating, because all the mathematics and
concepts taught in the context of static fields
can not only be taught but taught better and with
less aggravation with time-varying fields.
64
The Deductive Approach
In contrast to the inductive approach is the
deductive approach, that is, an approach in
which one begins with the general principles that
are accepted as true and then applies it to
particular cases, which in this case is beginning
with the complete set of Maxwells equations for
time-varying fields and then developing their
applications, as well as considering special
cases of static and quasistatic fields. This
approach permits the structuring of the course so
that (a) it constitutes the foundation for
students taking follow-on courses, as well as (b)
imparting the essentials for students taking this
course only in EM.
65
Deduction versus Induction
Deduction applies to the process in which one
starts with a general principle that is accepted
as true and applies it to a particular case,
arrives at a conclusion that is true if the
starting principle was true, as in All animals
die this is an animal therefore this will die.
Induction applies to the process by which one
collects many particular cases, finds out by
experiment what is common to all of them, and
forms a general rule or principle which is
probably true, as in Every animal I have tested
died probably all animals die.
66
The Deductive Approach (Continued)
Since the deductive approach begins with the
complete Maxwells equations, it provides an
appreciation of the fact that regardless of how
low the frequency is, as long as it is nonzero,
the phenomenon is one of electromagnetic waves,
resulting from the interdependence of
time-varying electric and magnetic fields. Then,
statics and quasistatics are treated as special
cases.
67
The Deductive Approach (Continued)
Furthermore, combining the deductive approach
with the thread of statics-quasistatics-waves
makes it quite clear that, along the frequency
spectrum, the quasistatic behavior approached
from the static (zero frequency) limit as an
extension of the static behavior to dynamic
behavior of first order in frequency is the same
as the low-frequency behavior approached from the
other (higher frequencies) side, by approximating
the exact dynamic solution for low frequencies.
This very important concept is not always clearly
understood or appreciated when the inductive
approach is employed.
68
The approach to the teaching of electromagnetics
And the deductive approach is the way of teaching
Maxwells equations as God said, as contrasted
with the inductive approach, which is the way in
which they were evolved by human intellect. I am
not a philosopher but it should not be difficult
to accept that Maxwell and others did not create
the equations they only discovered what God
said in the first place, through a series of
ingenious steps over time!
69
Knowledge is inherent man no knowledge comes
from outside. We say Newton discovered
gravitation. Was it sitting anywhere in a corner
waiting for him? It was in his own mind the
time came and he found it out. All knowledge that
the world has ever received comes from the mind
the infinite library of the universe is in your
own mind. The external world is simply the
suggestion, the occasion, which sets you to study
your own mind Swami Vivekananda
70
So, why is the teaching and learning of EM so
dreaded?
It is not entirely because of EM, but also
because of the way it is taught!
71
PoEM on why study EM!
To the students from all around the world And to
the students all over the world EMpowered by the
Jordan name And inspired by the AMRITA name I
offer to you this book on EM Beginning with this
poem which I call PoEM If you are wondering why
you should study EM Let me tell you about it by
means of this PoEM First you should know that the
beauty of EM Lies in the nature of its compact
formalism Through a set of four wonderful
EMantras Familiarly known as Maxwell's
equations They might be like mere four lines of
mathematics to you But in them lie a wealth of
phenomena that surround you Based on them are
numerous devices That provide you everyday
services Without the principles of Maxwell's
equations Surely we would all have been in the
dark ages Because there would be no such thing as
electrical power Nor would there be electronic
communication or computer Which are typical of
the important applications of ECE And so you see,
EM is fundamental to the study of ECE.
72
PoEM on why study EM! (Continued)
So, you are curious about learning EM Let us
proceed further with this PoEM First you should
know that E means electric field And furthermore
that B stands for magnetic field Now, the static
E and B fields may be independent But the dynamic
E and B fields are interdependent Causing them to
be simultaneous And to coexist in any given
space Which makes EM very illuminating And modern
day life most interesting For it is the
interdependence of E and B fields That is
responsible for electromagnetic waves In your
beginning courses you might have learnt circuit
theory It is all an approximation of
electromagnetic field theory So you see they put
the cart before the horse But it is okay to do
that and still make sense Because at low
frequencies circuit approximations are fine But
at high frequencies electromagnetic effects are
prime So, whether you are an electrical
engineer Or you happen to be a computer
engineer Whether you are interested in high
frequency electronics Or may be high-speed
computer communication networks You see,
electromagnetic effects are prime Studying the
fundamentals of EM is sublime.
73
PoEM on why study EM! (Continued)
If you still have a ProblEM with EM, Because it
is full of abstract mathematics, I say, my dear
ECE student who dislikes electromagnetics Because
you complain it is full of abstract mathematics I
want you to know that it is the power of
mathematics That enabled Maxwells prediction
through his equations Of the physical phenomenon
of electromagnetic radiation Even before its
finding by Hertz through experimentation In fact
it was this accomplishment That partly resulted
in the entitlement For the equations to be known
after Maxwell Whereas in reality they are not his
laws after all For example the first one among
the four of them Is Faradays Law expressed in
mathematical form You see, mathematics is a
compact means For representing the underlying
physics Therefore do not despair when you see
mathematical derivations Throughout your textbook
on the Fundamentals of Electromagnetics Instead
look through the derivations to understand the
concepts Realizing that mathematics is only a
means to extend the physics Think of you as
riding the horse of mathematics To conquer the
new frontier of electromagnetics Let you and me
together go on the ride As I take you through the
steps in stride, with grattitude!
74
The End
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