BEE 361 Lecture 1

8/9/2019 BEE 361 Lecture 1

1/17

BEE 361 /University of Washington Bothell

Lesson 1: Introduction toApplied Electromagnetics

Applied Electromagnetics B EE 361

8/9/2019 BEE 361 Lecture 1

2/17


Before we get started.

Read the Course Introduction

Make sure that you have achieved the proper course prerequisites

Purchase the textbook and begin reading Chapter 1

Fundamentals of Applied Electromagnetics by Ulaby, Michielssen, and Ravaioli, 6thEdition

Bring the following supplies to class

Paper and pen Textbook

Smith Charts (some available in class, or at www.microwaves101.com/downloads/smith.PDF)

Pocket Calculator

For now all other electronics (laptops, ipods, cellphones, etc.), out-of-sight

Review Course Schedule and note when HWs are due and Exam dates Get a jump start on HW #1

2
http://www.microwaves101.com/downloads/smith.PDFhttp://www.microwaves101.com/downloads/smith.PDF

8/9/2019 BEE 361 Lecture 1

3/17


Applications of Electromagnetics

3

8/9/2019 BEE 361 Lecture 1

4/17


Electromagnetics in Telecommunications

4

8/9/2019 BEE 361 Lecture 1

5/17


Electromagnetics in Computer Technology

5

8/9/2019 BEE 361 Lecture 1

6/17


Known Forces in Our Present Universe

1. Gravitational Forces

Force that attracts masses to one another Very, Very Weak

2. Strong Forces

Holds Protons, and Neutrons, (Nucleons) together Extremely Short Range

3. Weak Forces

Accounts for certain kinds of radioactive decay Short Range, Very Weak

4. Electromagnetic Forces

Predominant Force in everyday life Very, Very Strong over Large Range

FG

FEM

Proton

Quarks

FG

Electromagnetic Forces responsible for keeping the soccer ball from going through

the earth, friction, chemical forces that bind molecules, colliding billiard balls, etc. etc.

6

8/9/2019 BEE 361 Lecture 1

7/17


Gravitational Force

Force exerted on mass 2 by mass 1

Gravitational field induced by mass 1

7

8/9/2019 BEE 361 Lecture 1

8/17


What Electric Force do Charges Exert?

Coulombs Law

The E lect r i c Fo r ce F21 exerted by Charge q1 on Charge q2 :

where

and constant k is:

2

12

211221

R

qqRke

F =

2112

2112

tofromDistance:

tofromctorUnit ve:

qqR

qqR

1=k

04

1

=k41=k

Gaussian (cgs)International System of Units

SI (mks)Heavyside - Lorentz

F/m10x8.85 -12=o

Electrical Permittivity of free space

1q

2q

21eF

12R

12R

8

8/9/2019 BEE 361 Lecture 1

9/17


What are the Rules and Properties of Charge?

1. Charge comes in two varieties: plus +q (positive) and minus q (negative)

Opposite charges cancel one another and come in almost exactly equal amounts to agreat degree of precision in bulk matter. Due to the large forces created by charge, if

matter were unbalanced, matter would explode!

2. Charge is conserved: it can be neither created nor destroyed

This is a conservation law of our present known universe in that before or after any

action, the net amount of charge remains the same. Whew, lucky for us. Imagine if

charge could spontaneously appear in your circuit, or perhaps disappear in your

circuit, and appear half way across the universe!

3. Charge is quantized: it comes in only integral (n=0,1,2,3) packets of

where e=1.609 x 10-19Coulombs

This is because the charge of fundamental particles (protons, nuetrons, electrons,

pions, etc.) is only +e, -e, or zero. This did not have to be so. Quarks which form

nucleons have a property similar to charge, however they come in one or two

multiples of 1 3 .

9

8/9/2019 BEE 361 Lecture 1

10/17


What is the Electric Field?

Definition of Electric Field Due to Charge q1

:

The E l ec t r i c F i e l d Eoriginatingfrom charge q1 is definedas:

where

and constant k is: k = 4in SI (mks) Units

where 0 =8.854 x 1012Farrad per meter (F/m) is the

permittivity of free space

2

12

112

2 R

qRk

q

21e F

EE ==

2112

2112

tofromDistance:

tofromctorUnit ve:

qqR

qqR

Note that q

2

acts as a test charge that can be placed anywhere to

determine the Electric Field that originates from q

1

.

Volts per meter (V/m)

10

8/9/2019 BEE 361 Lecture 1

11/17


Properties of the Electric Field

1. The Electric Field lines originate from charge itself; they begin on positive

charge (source) and terminate on negative charge (sink)

Even though this designation is by convention, charge being the origin of the electric

field has major implications that we will discuss in terms of the divergence of this field.

2. The Electric Field obeys the P r i n c i p a l o f L i n e a r Sup er p o si t i o n

The total vec t o r Electric Field at a point in space die to a system of point charges is

equal to the v ect o r sum of the Electric Fields at that point due to the individual

charges. We will discuss this during the 2ndhalf of the lecture.

3. The Electric Field applied to matter creates a counter field that diminishesthe Total Electric Field in the matter

We will discuss this in the next slide and during the 2ndhalf of the lecture.

11

8/9/2019 BEE 361 Lecture 1

12/17


Electric Field in a Material

12

8/9/2019 BEE 361 Lecture 1

13/17


What is the Magnetic Field?

Electric charges can be isolated, but magnetic poles always exist in pairs.

Magnetic field induced by a

current in a long wire

Magnetic permeability of free space

Hans Christian Oersted

(1820)

Biot-Savart Law

(1820)

Measures magnetic

field with a compassMagnetic Flux Density

B

Tesla (T)

orWeber/meter2(Wb/m2)

Right Hand Rule

N

S

N

N

S

S

Cut

inHalf

13

8/9/2019 BEE 361 Lecture 1

14/17


Force on Charge in a Magnetic Field

+

+q

I2

Current defined as flow of positive (+q) charge

Second wire with current

flowing added to measure

Force.

Fm12

Fm21

Andr-Marie Ampre(1820)

where again by definition,

Further discussion in class

during 2ndhalf of lecture

14

This magnetic force is equivalent to the

electrical force that would be exerted on

the particle by the electric field Em given

by

8/9/2019 BEE 361 Lecture 1

15/17


Maxwells Equations for EM Fields Wow ! !

How did we get from there to here? Well, a lot of discoveries and experiments in the

18thAnd 19thcenturies by Ampere, Gauss, and Farraday (among others); unification

of all of these laws by Maxwell; and restating Maxwells Equations into compact

vector calculus form by Heavyside.

15

8/9/2019 BEE 361 Lecture 1

16/17


EE361 Course Flow

The Three Branches of Electromagnetics

1) Transmission Line Theory

2) Vector Algebra and Vector Calculus

3)

4)

Electrostatics

=

= 0

Magnetostatics

= 0

=

Dynamics

Time varying fields and their implications for Circuit Theory

including Kirchoffs Voltage and Current Laws (KVL&KCL).

When they hold! and When they break down!

16

8/9/2019 BEE 361 Lecture 1

17/17


Prior to Starting Transmission Lines Review

Complex Numbers = + = , =

Phasor Analysis

= =

Waves

(, ) = cos

17

Documents

BEE 361 Lecture 1