Microwaves

Application Note of Electromagnetic Wave Propagation:

Microwaves are EM waves whose frequencies range from approximately 300 MHz to 1000 GHz.

About Microwaves

• The signal from

1. An AM radio station is about 1 MHz.


2. An FM station is about 100 MHz.

• Microwave oven operates at 2.4 GHz.


• Satellite television receiver operates at about 4 GHz.


• Police radar works at about 22 GHz.


• Microwaves behave more like rays of light than ordinary waves.


• Microwave spectrum provides more communication channels than the radio an TV bands.

Microwave System consists of:

• Transmitter including a microwave oscillator, waveguides, and transmitting antenna.


• Receiver including a receiving antenna, transmission line or waveguide and microwave amplifiers.

Use of microwaves:

• Telecommunications
  
  
  
  • The transmission of analog or digital information from one point to another.
  
  
  • Microwaves propagate along a straight line like light rays and are not bent by the ionosphere.
  
  
  • Communication satellite is a microwave relay station that is used to link two or more ground based transmitters and receivers.
  
  
  • The satellite receives signals at one frequency, amplify them and transmits at another frequency.


• Radar System
  
  
  
  • Radar is used to detect aircraft, guide supersonic missiles, observe and track weather patterns and control flight traffic at airports.
  
  
  • Radar is also used in burglar alarms, garage door openers and police speed detectors.


• Heating
  
  
  
  • Microwave energy is more easily directed, controlled and concentrated than low frequency EM waves.
  
  
  • When the magnetron oscillates, microwave energy is extracted from the resonant cavities.
  
  
  • The reflections from the stationary walls and the motion of the stirring fan cause a microwave energy to be well distributed. Thus the microwave enables the cooking process to be fast.
  
  
  • Microwave heating properties also are used in physical diathermy and in drying potato chips, paper, cloth etc.


• Radio astronomy


• Land Surveying


• Meteorology


• UHF Television


• Medicine


• Identification Systems

Paramjeet Singh Jamwal

Lecturer

Guru Nanak Education Trust Group Of Institutions, Roorkee