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Microwave

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18 views10 pages

Microwave

Uploaded by

skhushboo10
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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MICROWAVE AND ANTENNA THEORY

Introduction to Microwave
 History of microwaves
 Microwave Frequency Bands, characteristics, advantages and
disadvantages, applications of microwaves in various fields.
 Microwave radiation Hazards.
 Safety and precautions.
Electromagnetic Spectrum consists of entire range of electromagnetic radiation. Radiation is the
energy that travels and spreads out as it propagates. Microwaves are EM waves whose
frequencies range from 1 GHz to 1000 GHz.

Properties of Microwaves
Following are the main properties of Microwaves.
 Microwaves are the waves that radiate electromagnetic energy with shorter
wavelength.
 Microwaves are not reflected by Ionosphere.
 Microwaves travel in a straight line and are reflected by the conducting surfaces.
 Microwaves are easily attenuated within shorter distances.
 Microwave currents can flow through a thin layer of a cable.
Advantages of Microwaves
There are many advantages of Microwaves such as the following −
 Supports larger bandwidth and hence more information is transmitted. For this
reason, microwaves are used for point-to-point communications.
 More antenna gain is possible.
 Higher data rates are transmitted as the bandwidth is more.
 Antenna size gets reduced, as the frequencies are higher.
 Low power consumption as the signals are of higher frequencies.
 Effect of fading gets reduced by using line of sight propagation.
 Provides effective reflection area in the radar systems.
 Satellite and terrestrial communications with high capacities are possible.
 Low-cost miniature microwave components can be developed.
 Effective spectrum usage with wide variety of applications in all available
frequency ranges of operation.
Disadvantages of Microwaves
There are a few disadvantages of Microwaves such as the following −
 Cost of equipment or installation cost is high.
 They are hefty and occupy more space.
 Electromagnetic interference may occur.
 Variations in dielectric properties with temperatures may occur.
 Inherent inefficiency of electric power.
Applications of Microwaves
There are a wide variety of applications for Microwaves, which are not possible for
other radiations. They are −
Wireless Communications

 For long distance telephone calls


 Bluetooth
 WIMAX operations
 Outdoor broadcasting transmissions
 Broadcast auxiliary services
 Remote pickup unit
 Studio/transmitter link
 Direct Broadcast Satellite DBS
 Personal Communication Systems PCSs
 Wireless Local Area Networks WLANs
 Cellular Video CV systems
 Automobile collision avoidance system
Electronics

 Fast jitter-free switches


 Phase shifters

 HF generation
 Tuning elements
 ECM/ECCM Electronic Counter Measure systems
 Spread spectrum systems
Commercial Uses

 Burglar alarms
 Garage door openers
 Police speed detectors
 Identification by non-contact methods
 Cell phones, pagers, wireless LANs
 Satellite television, XM radio
 Motion detectors
 Remote sensing
Navigation

 Global navigation satellite systems


 Global Positioning System GPS
Military and Radar
 Radars to detect the range and speed of the target.
 SONAR applications
 Air traffic control
 Weather forecasting
 Navigation of ships
 Minesweeping applications
 Speed limit enforcement
 Military uses microwave frequencies for communications and for the above
mentioned applications.
Research Applications

 Atomic resonances
 Nuclear resonances
Radio Astronomy

 Mark cosmic microwave background radiation


 Detection of powerful waves in the universe
 Detection of many radiations in the universe and earth’s atmosphere
Food Industry

 Microwave ovens used for reheating and cooking


 Food processing applications
 Pre-heating applications
 Pre-cooking
 Roasting food grains/beans
 Drying potato chips
 Moisture levelling
 Absorbing water molecules
Industrial Uses

 Vulcanizing rubber
 Analytical chemistry applications
 Drying and reaction processes
 Processing ceramics
 Polymer matrix
 Surface modification
 Chemical vapor processing
 Powder processing
 Sterilizing pharmaceuticals
 Chemical synthesis
 Waste remediation
 Power transmission
 Tunnel boring
 Breaking rock/concrete
 Breaking up coal seams
 Curing of cement
 RF Lighting
 Fusion reactors
 Active denial systems
Semiconductor Processing Techniques

 Reactive ion etching


 Chemical vapor deposition
Spectroscopy

 Electron Paramagnetic Resonance EPR or ESR Spectroscopy


 To know about unpaired electrons in chemicals
 To know the free radicals in materials
 Electron chemistry
Medical Applications

 Monitoring heartbeat
 Lung water detection
 Tumour detection
 Regional hyperthermia
 Therapeutic applications
 Local heating
 Angioplasty
 Microwave tomography
 Microwave Acoustic imaging
MICROWAVE RADIATION HAZARDS

 Microwaves are widely used in households, industry, communications,


and medical and military buildings, and they provide substantial
contributions to the development of human society.
 However, with its popularization, increasing attention has been paid to
its influence on humans. Electromagnetic radiation can be absorbed by
organisms, in which it causes a series of physiological and functional
changes. Many intricate electrical activities occur in the central nervous
system, including learning and memory, which are therefore vulnerable
to electromagnetic radiation.
 Moreover, the popularization of mobile phones has made them the main
source of brain exposure to radiation. Therefore, the central nervous
system is considered one of the most sensitive organs that is targeted by
microwave radiation.
 A large number of studies have shown that microwave radiation can
cause a series of adverse reactions in the central nervous system,
including sleep disorders in addition to learning and memory
impairments.

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