its about the paractical applications of microwaves

1. • Muhammad Umer Shehzad
• Jawad Fakhir
• Sir Haissam Sattar

2. Introduction to Microwaves
Properties of Microwaves
Advantages/Disadvantages of Microwaves
Waveguide
Applications of Microwaves
Microwave oven
Radar
Wireless Mobile Charging
Others Applications

3. In physics, a wave is disturbance or oscillation that travels
through matter or space, accompanied by a transfer of
energy.
There are two main
types of waves.
Mechanical Waves
Electromagnetic
Waves
• Radio waves
• Microwaves
• Infrared radiation
• Visible light
• Ultraviolet radiation

4. 4
Microwaves are electromagnetic waves
Frequency range 300MHz-
300Ghz
Wavelengths range
in air
100cm-
1mm
The word microwave means “very short wave”
Microwaves is the
shortest wavelength
region of the radio
spectrum and a part
of the
electromagnetic
spectrum

5. 5
Microwaves Frequency Bands

6. Properties of Microwaves
6
1.Electromagnetic
radiation of short
wavelength
2.Can reflect by
conducting surface
like optical waves.
3.M.W current flows
through outer layer
of conductor
4.Microwaves are
easily attenuated
5.They are not
reflected by
ionosphere

7. 7
Microwaves have large
bandwidths
Improved Directive
properties.Can be
focused in a specified
direction
Fading effect and
reliability.
Due to LOS and high
frequency fading effect is
very low
Transmitter/Receiver
power requirements are
pretty low at microwave
frequencies

8. 8
Microwave band ranging from 300MHz-10GHz are capable of freely
propagating through atmosphere
This helps in astronomical research of space
in the study of microwave radiations from
the sun and stars

9. Because of high frequency,
more data can be sent.
High
bandwidth,hi
gher speeds
Because of their short
wavelength,microwaves use
smaller antennas
Smaller
antennas
produce a
more focused
beam

11. Functional Block Diagram of a
Communication System
Input signal
(Audio, Video, Data)
Input Transducer
Transmitter
Output Transducer
Receiver
Output signal
(Audio, Video, Data)
Channel
Electrical System
Wire
or
Wireless

12. Antenna and Wave Propagation
Surface Wave
Direct Wave
Sky Wave
Satellite
communication
Microwave &
Millimeter Wave
Earth
Ionsphere
Transmitting
Antenna
Receiving
Antenna
Repeaters(Terrestrial communication)
50Km@25fts antenna

13. 13
A Hollow metallic tube of uniform cross section for transmitting
electromagnetic waves by successive reflections from the inner walls of the
tube is called waveguide.

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Electromagnetic waves at frequencies greater than
3GHz; transmission through cables becomes difficult.
Reason
This is due to losses in the solid cable and the
dielectric use to support the cable.
So, we use waveguide
which is a hollow
metallic

15. 15
Waveguides are used to carry
energy from one equipment to
another
e.g. In Antennas
transmitter power
to antenna and
microwave signal
from antenna to
receiver
Waveguides are made from copper,
aluminum or brass
The metals are
extruded into long
rectangular or
circular pipes
The energy to be transmitted is
injected from one end of the
waveguide through probes
The electric and
magnetic field of
signals bounce off
the walls back and
forth.

16. 16
EM field configuration can be determined from
Maxwell’s equation.
There are number of configurations and each
configuration is known as mode.
Possible
modes
Transverse
Electromag
netic
Transverse
Electric
Transverse
Magnetic
Hybrid

17. Components of Electric and Magnetic
Field Intensities in an EM wave
17
O
X
Y
Z
Ex,
Hx
Ez, Hz
Ey,Hy

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2. Transverse Electric (TE) wave: Here only the electric field is
purely transverse to the direction of propagation and the magnetic
field is not purely transverse. (i.e.) E z = 0, Hz ≠ 0
1.Transverse Electro Magnetic (TEM) wave:
Here both electric and magnetic
fields are directed components.(i.e.) Ez=0 and Hz=0
2.Transverse Electric (TE) wave:
The electric field component is
purely transverse to the direction of propagation.(i.e.) Ez=0 and Hz≠0

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3.Transverse Magnetic (TM) wave:
The magnetic field component is
purely transverse to the direction of propagation.(i.e.) Ez≠0 and Hz=0
4.Hybrid (HE) wave:
Here neither electric nor magnetic fields are
purely transverse to the direction of propagation.(i.e.) Ez≠0 and Hz≠0

20. 20

21. 21
Rectangular Waveguides
 Any shape of cross section of a waveguide
can support electromagnetic waves of
which rectangular and circular waveguides
have become more common.
 A waveguide having rectangular cross
section is known as Rectangular
waveguide

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Rectangular waveguide
Dimensions of the waveguide which determines the operating
frequency range

23. 23
1.The size of the waveguide determines its
operating frequency
2.The frequency of operation is determined
by dimension ‘a’ which is usually made one
half the wavelength at lowest frequency of
operation.
3.At cutoff frequency and below, the
waveguide will not transmit energy.

24. 24
Wave paths in a waveguide at various frequencies
Angle of incidence(A) Angle of reflection (B)
(A = B) (a) At high
frequency
(b) At medium
frequency
( c ) At low frequency
(d) At cutoff
frequency

25. 25
Wave propagation
 When a probe launches energy into the
waveguide, the electromagnetic fields bounce
off the side walls of the waveguide as shown in
the above diagram.
 The angles of incidence and reflection depend
upon the operating frequency. At high
frequencies, the angles are large and therefore,
the path between the opposite walls is relatively
long as shown in Fig.

26. 26
At lower frequency, the angles decrease and the path between the sides
shortens.
When the operating frequency is reaches the cutoff frequency of the
waveguide, the signal simply bounces back and forth directly between the side
walls of the waveguide and has no forward motion.
At cut off frequency and below, no energy will propagate.

27. 27
• It is used for bends, twists or in applications where certain criteria may not be
fulfilled by normal waveguides.
• Figure below shows some of the flexible waveguides:

29. How a Microwave Oven Works?

30. History
 Invented Accidentally By Dr. Percy Lebaron Spencer.

31. Working Principle
31
Microwave radiations generated by a magnetron pass through the exposed food,
create dielectric heating within the food, this is the basic principle on which a
microwave oven works.
Dielectric Heating

32. How the Oven Works
 Electricity from the wall outlet travels through the power cord and enters the
microwave oven through a series of fuse and safety protection circuits
 When the oven door is closed, an electrical path is also established through a series
of safety interlock switches

33.  Sensing That All Systems Are Set To Go, The Signal Activates Triac Producing A Voltage Path
To The High-voltage Transformer.
 The High-voltage Transformer Along With A Special Diode And Capacitor Arrangement
Increases The Typical Household Voltage From ~220 Volts To ~3000 Volts

34.  The magnetron converts the high voltage into the microwave frequency for cooking.
 The microwave energy is transmitted into a waveguide.
 The waveguide feeds the energy to the stirrer blade and into the cooking area.
 When the door is opened, or the timer reaches zero, the microwave energy stops.

36. How Foods Get Cooked
 The microwaves that penetrate the food have an electric field that oscillates 2.45
billion times a second, a frequency that is well absorbed by polar liquid molecules
such as water, sugars, fats and other food molecules.
 Water interacts with the microwave:
 flipping its orientation back and forth very rapidly
 bumping into one another and producing heat, cooking the food.

37. Radar
37

38. Introduction
38
Radar Radio Detection and Ranging
 A System For Detecting The Presence, Direction, Distance, And Speed Of Aircraft,
Ships, And Other Objects, By Sending Out Pulses Of Radio Waves Which Are
Reflected Off The Object Back To The Source.
 The Time Delay Between The Transmitted Pulse And The Received Echo Can Be
Used To Determine The Distance To The Target .

39. Basic Principle and Operation Of Radar

40. RADAR FUNCTIONS
TRANSMITTER:
 Generate radio waves
 Perform modulation
 Amplification to high power
RECIEVER:
 High sensitivity
 Very low noise
 Ability to discern a received signal from background noise
PROCESSING & CONTROL:
 It regulates the rate at which pulses are sent (PRF).
 Synchronizes the function between Transmitter, Receiver,
display, duplexer etc.

41. DUPLEXER:
 A switch to alternatively connect Tx and Rx to antenna.
ANTENNA:
 Takes radar pulses from transmitter and puts into the air.
 Focuses energy into the well designed beam.
 Antenna is of two types
1) Physically moving
2) Electronically steered
DISPLAY:
Display received information to the operator. It is of two types
1) PPI
 Used for surface search and navigation
2) A-Scan
 Used for gunfire control

42. MAIN TYPES OF RADAR
There are two main types of radar:
1)Primary Radar
 Continuous wave Radar
 Pulse Radar
2)Secondary Radar SSR

43. 43
1)CONTINUOS WAVE RADAR:
 Employs continual RADAR transmission
 Separate transmit and receive antennas
 Relies on the “DOPPLER SHIFT”

44. 44
2)PULSE RADAR:
 The PULSE radar is the more conventional radar, which transmits a
burst of radar energy and then waits for the energy (or echo) to be
reflected back to the antenna.
 Since radar waves travel at the speed of light, range from the return can
be calculated.

45. Applications of Radar

46. MILITARY
 Target Detection, Target Tracking & Weapon Control
 Tracks The Targets, Directs The Weapon To An Intercept And Assess
The Effectiveness Of Engagement

47.  Weather Observation
 Planetary Observation
 Below Ground Probing
REMOTE SENSING

48.  Used To Safely Control Air Traffic In The Vicinity Of The
Airports.
 Mapping Of Regions Of Rain In The Vicinity Of Airports &
Weather.
AIR TRAFFIC CONTROL

49.  Radar Speed Meters Are Used By Police For Enforcing
Speed Limit.
LAW ENFORCEMENT &
HIGHWAY SAFETY

50. • Airborne Weather Avoidance Radar Outlines The Regions
Of Precipitation & Dangerous Wind Shear
• Low Flying Military Aircrafts Rely On Terrain Avoidance &
Terrain Following Radars To Avoid Collision With High
Terrain & Obstructions
AIRCRAFT SAFETY &
NAVIGATION

51. • Radar Is Found On Ships & Boats For Collision Avoidance & To
Observe Navigation Buoys, When The Visibility Is Poor
• Shore Based Radars Are Used For Surveillance Of Harbours &
River Traffic
SHIP SAFETY

52. • Space Vehicles Have Used Radar For Landing On The
Moon And Other Planets.
• Used For Planetary Exploration
• Ground Based Radars Are Used For Detection & Tracking
Of Satellites & Other Space Objects
• Used For Radio Astronomy
SPACE

53. MINE INSPECTION

54. LOCATING UNDER GROUND PIPES

55. Wireless Charging of Mobile Phones Using
Microwaves
55

56. INTRODUCTION
 Objective—to Recharge Any Mobile Phone Independent Of Particular Mobile
Charger.
 Mobile Phones Becoming Basic Part Of Life
 Recharging Of Mobile Phones Is A Big Problem
 More You Talk More The Mobile Get Charged!
 No Separate Mobile Charger
 Additives To Mobile Handsets:
 Sensor
 Rectenna
56

57. Microwave region of electromagnetic spectrum
 We choose s –band of microwave region(2-4GHz)
 We Use License free 2.45 GHz Industrial, Scientific and Medical (ISM)
radio bands
57
Designation Frequency range
L Band 1 to 2 GHz
S Band 2 to 4 GHz
C Band 4 to 8 GHz
X Band 8 to 12 GHz
Ku Band 12 to 18 GHz
K Band 18 to 26 GHz
Ka Band 26 to 40 GHz
Q Band 30 to 50 GHz
U Band 40 to 60 GHz

58. Principle of Operation &
Block Diagram
Transmitting
station with the
microwave
transmitter
sensor
Rectenna
RF cable
circulator
waveguide
Slotted waveguide
Antenna
mobile signal
 Microwave signal is transmitted from transmitter along with
message signal using slotted waveguide antenna at frequency
2.45 GHZ.
 The sensor search for the mobile signal , in addition it has a
“RECTENNA”.
 Rectenna receives the transmitted power and converts the
microwave power to DC power.

59. TRANSMITTER SECTION
Consists of two parts
Magnetron
Slotted waveguide antenna
59

60. MAGNETRON
• Magnetron is a vacuum tube oscillator that generates
high-power electromagnetic signals in the microwave
frequency range.
60

61. Working Principle
61
 When a charge/charge particle accelerates in space, it generates electromagnetic
waves.
 This statement is the derivation of Maxwell’s law which says that a classical
electromagnetic radiation is ultimately generated when a charged particle is
accelerated through space.

62. Working
62

63. Slotted waveguide antenna
 It is an Omni-directional Antenna.
 It is used as ideal power transmitter
(because of its high aperture efficiency
>95%) .
 It has high power handling capacity .

64. RECEIVER SECTION
 Basic additions to mobile phone
 Sensor
 Rectenna
64

65. SENSOR
 Simple circuit which detects whether the user is making a call
 Simple F to V converter, this would serve our purpose
 Operating frequency of mobile phone operators for GSM system for mobile
communication in Pakistan is 900MHZ to 1800MHZ
 Simple yet powerful F to V converter is LM2907
 On the reception of the microwave signal ,the sensor circuitry directs rectenna circuit to
ON
 Rectenna circuit converts microwave energy to dc output
 Mobile phone begins to charge using the microwave power as long as the user talks over
cell phone.

66. RECTENNA
 A rectifying antenna called a rectenna receives the transmitted power
and converts the microwave power to direct current (DC) power.
 The Schottky diode rectifies the AC current induced in the antenna by
the microwaves, to produce DC power, which powers a load connected
across the diode.
 Schottky diodes are usually used because they have the lowest voltage
drop and highest speed and therefore have the lowest power losses
due to conduction and switching.
Circuit Design

67. Implementation
 Recently NOKIA has launched this wireless charging technology
in its new recent mobile model “ NOKIA LUMIA 1020”.

68. Advantages
The need of different types of chargers by different
manufacturers is totally eliminated
Lower risk of ELECTRICAL SHOCK or shorting.
Convenience.
Get Charged as we make call.
 Only one microwave transmitter can serve to all the
service providers in that area.

69. Disadvantages
 Wireless transmission of the energy causes some
drastic effects to human body, because of its radiation.
 Process is of high cost.
 Network Traffic may Cause Problem in charging

70. Other Applications Of Microwaves
70

71. Homeland Security Applications
Potential Security Applications
 Detection of hidden weapons and explosives
 Detecting non-metallic weapons
 Postal screening of envelopes for bacteria
 Chem/bio detection
Security screening wand
Explosives
Stand-off detection
Postal screening
Envelope

72. Terahertz Images Can Reveal Objects Concealed
Under Cloth, Paper, Tape, Even Behind Walls
Objects Concealed Under clothes Knife Wrapped in Newspaper

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