Microwave Amplifiers - Single Stage Design [1]
INTRODUCTION
We limit this tutorial to single stage transistor amplifiers. Background material covering characteristics of
microwave transistors and gain and stability of general two port amplifier circuits c
Exact Derivation of R
z'
R r
Far-field region z'
z=0 Dipole
z=0
z'cos
R = x 2 + y 2 + ( z z ) r2 = x2 + y2 + z2 z = r cos
2
= x 2 + y 2 + z 2 + ( 2 zz + z2 ) Now let
Hence
R = r 2 + ( 2rz cos + z2 ) 1 = r 1 + 2 ( 2rz cos + z2 ) r
1/ 2
Binomial expansio
Image Theorem_Hon Tat Hui
The Image Theorem
For antennas mounted over or near a ground plane (a very large
perfectly conducting plane), virtual sources (images) can be place below
the ground plane to account for reflections from the ground plane. After
in
Maximum Radiation Direction_Hon Tat Hui
Maximum radiation direction of (AF)n
d ( AF ) n
1 sin (N / 2 )
= d
/ d = 0
d
N sin ( / 2 )
N
N 1
N
cos sin
sin cos
2
2
2
2
2
2 =0
2
sin
2
N
N
N
1
= cos sin
sin cos
2
2
2
2
2
2
N
i.e., N tan = tan
2
2
The last
NUS/ECE
EE4101
National University of Singapore
Department of Electrical and Computer Engineering
EE4101 RF COMMUNICATIONS
First Semester, 2011/12
Dr. Hon Tat Hui
Hon Tat Hui
1
Revision of Maxwells Equations
NUS/ECE
EE4101
Revision of Maxwells Equations
1
NUS/ECE
EE4101
Revision of Plane Wave Propagation
See animation Plane Wave Viewer
1 Plane Waves in Lossless Media
In a source free lossless medium, J = = = 0.
Maxwells equations:
H
E = -
t
E
H =
t
E = 0
H = 0
Hon Tat Hui
1
Revision of Plane Wave Propa
NUS/ECE
EE4101
Solution of the Inhomogeneous Helmholtz Equation
Equation:
2 A ( R ) + k 2 A ( R ) = J ( R )
Soultion:
(1)
e jkR
A( R ) =
J ( R' ) R dv '
4 v '
(2)
R = ( r , , ) =field point, R' = ( r ', ', ' ) =source point
R = R R'
_
Hon Tat Hui
Solutio
Tutorial 2 Antennas
Question 1
A radiator approximates to an electric dipole of length dl = 250 m and radiates at a frequency
of 60 kHz. Assuming that the current is maintained constant over the length, determine the
radiation resistance Rr of the radiato
Tutorial 3 Antenna Arrays
Question 1
A uniform linear array of 20 isotropic elements is placed along the x-axis with an interelement spacing d = /4 and a progressive phase shift of . Calculate the values of (within
the range: - < ) for the following desig
NUS/ECE
EE4101
Waveguides
At high frequencies, the loss of electromagnetic waves traveling
along transmission lines due to conductor resistance and radiation
leakage becomes exceedingly large. To alleviate this problem,
hollow waveguides can be used. We w
Effective Area and Gain_Hon Tat Hui
Proof of A e (, ) =
Extracted from the book:
2 2 D(, ) = g (, ) 4 4
Kai Fong Lee, Principles of Antenna Theory, John Wiley & Sons, 1984, pp. 74-76.
1
Effective Area and Gain_Hon Tat Hui
2
Coordinate Transformation Formula Sheet
Table with the Del operator in rectangular, cylindrical, and spherical coordinates
Operation
Cartesian coordinates (x,y,z)
Cylindrical coordinates
(,z)
Definition
of
coordinates
= cos x + sin y
= sin x + cos y
Def
NUS/ECE
EE4101
Antenna Fundamentals
1 Introduction
Antennas are device designed to radiate electromagnetic
energy efficiently in a prescribed manner.
It is the current distributions on the antennas that produce
the radiation. Usually these current distrib
B al ns:W hatT heyD o
u
And H ow T heyD o l t
By Roy lV. Lewallen,* IVTEL
* 5 4 7 0 S W 1 5 2 n dA v e . , B e a v e r t o n , R 9 7 0 0 7
O
I've always been a bit botheredby balunst
t
s i n c e I w a s n e v e r s u r e w h a t t h e y a r e s u p p o s
EE4101 RF Communications
Part B
Prof TS Yeo
1
REE4101 RF Communications Part B
House Keeping
Prof T S Yeo
E4-07-19/E1-05-05
eleyeots@nus.edu.sg
6516 2119 or ext 62119
Assessments
Examination 70%
Class Test (Prof Hui) 10%
Problem-based Learning 10%
Labora
EE4101 RF Communications
Part B
Prof TS Yeo
1
EE4101 RF Communications Part B
Impedance Matching - Revision
Matching using Stub Smith Chart
Z
L2
L1
in
Matching network
Example: Z = 62.5 , in = 0.6/50o , z = 62.5/50 =
1.25, y = 1/1.25 = 0.8
2
EE4101 RF Co
EE4101 RF Communications
Part B
Prof TS Yeo
1
EE4101 RF Communications Part B
Receivers
Simple frequency conversions
Rectification
Envelop detection
Mixing
2
EE4101 RF Communications Part B
Receiver
Simple transmitter
Input: baseband signal
at fm (voice
EE4101 RF Communications
Part B
Prof TS Yeo
1
EE4101 RF Communications Part B
RF systems - Overview
Most operations are in linear
(small-signal) region.
Extend of this region (defined
either by input power or
output power) is called the
Dynamic Range.
Pr
EE4101 RF Communications
Part B
Prof TS Yeo
1
REE4101 RF Communications Part B
RF Generation
RF Generation:
Microwave oscillators convert DC power into RF power
Solid-state oscillators use active devices (diodes or transistors)
in conjunction with mat
EE4101 RF Communications
Smith Chart and Impedance Matching
- additional lecture material
by
Marek E Bialkowski
EE4101 Smith Chart / 1
ECE NUS
Lossless Transmission Line
Lossless
Terminated in ZL
Terminated
We recall some results, which we obtained for a
EE4101 RF Communications - Assignment
NATIONAL UNIVERSITY of SINGAPORE
Faculty of Engineering
Electrical & Computer Engineering Department
EE4101 RF Communications
Assignment
DESIGN A MICROSTRIPLINE BAND-PASS FILTER
1
OBJECTIVES
a) To design a microstripl
EE4101 RF Communications MW1
NATIONAL UNIVERSITY of SINGAPORE
Faculty of Engineering
Electrical & Computer Engineering Department
EE4101 RF Communications
Experiment MW1
GUNN OSCILLATOR
1
OBJECT
To become familiar with the operation of the Gunn oscillator
NUS/ECE
EE4101
Antenna Arrays
1 Introduction
Antenna arrays are becoming increasingly important in
wireless communications. Advantages of using antenna
arrays:
1. They can provide the capability of a steerable beam
(radiation direction change) as in smart
NUS/ECE
EE4101
Electromagnetic Radiation
1. Radiation Mechanism
When electric charges undergo acceleration or
deceleration, electromagnetic radiation will be
produced. Hence it is the motion of charges (i.e.,
currents) that is the source of radiation.
Yet