Application Note of Electromagnetic Wave Propagation:
Microwaves are EM waves whose frequencies range from approximately 300 MHz to 1000 GHz.
- The signal from
- An AM radio station is about 1 MHz.
- 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:
- 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.
- 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
- UHF Television
- Identification Systems
Paramjeet Singh Jamwal
Guru Nanak Education Trust Group Of Institutions, Roorkee