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antennasystem-190928171019.pptx
- 2. Antenna In radio andelectronics, an antenna, or aerial, is an electrical device which converts electric power into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver.
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- 5. Antenna According to theirapplications and technology available, antennas generally fall in one of two categories: 1. Omnidirectional 2. Directional
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- 7. Omnidirectional Antenna only weaklydirectional antennas which receive or radiate more or less in all directions. These are employed when the relative position of the other station is unknown or arbitrary. They are also used at lower frequencies where a directional antenna would be too large, or simply to cut costs in applications where a directional antenna isn't required.
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- 9. Directional Antenna Directional orbeam antennas which are intended to preferentially radiate or receive in a particular direction or directional pattern.
- 10. FUNDAMENTAL PARAMETERS OFANTENNAS • FREQUENCY • DIRECTIVITY • ANTENNAEFFICIENCY • ANTENNAGAIN • FRISS TRANSMISSION EQUATION • ANTENNANOISE TEMPERA TURE • WAVELENGTH • POLARIZATION
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- 13. • FRISS TRANSMIONEQUATION • ANTENNANOISE TEMPERA TURE Ts = Tin + Te
- 14. • W A VELENGTH λ =c / f
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- 16. TYPES OF POLARIZATION • CROSSPOLARIZATIOIN • CIRCULAR POLARIZATION
- 17. TYPES OFANTENNAS • TRA VELLINGW A VE ANTENNAS • LOG-PERIODIC ANTENNAS • APERTUREANTENNAS • WIREANTENNAS • REFLECTOR ANTENNAS
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- 19. Yagi Antenna • Inventedby Shintaro Uda in 1926. • Consist of reflector, director and driven element. • It is unidirectional antenna. • High gain > 10 dB • Frequency range – 3MHz-3GHz
- 20. Yagi – Uda(Advantages) • High gain and good front to back ratio. • It has narrow bandwidth. • It is fixed frequency device. • Greater directivity due to director and reflector.
- 21. Yagi Antenna (Applications) WorldWar -II Messerschmitt 1110 fighter aircraft Rooftop television
- 22. LOG-PERIODIC ANTENNAS BOW TIEANTENNA LOG-PERIODIC ANTENNA LOG-PERIODIC DIPOLE ANTENNA
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- 24. Log-Periodic Antenna • Inventedby Dwight Isbell and Raymond DuHamel in 1958. • It is unidirectional antenna. • Length and spacing of the elements increase logarithmically. • Frequency-independent antenna. • Less directivity as compare to YAGIANTENNA. • Frequency range – VHF and UHF band.
- 25. Log-Periodic Antenna (Advantages) •It is broadband antenna. • It is unidirectional antenna. • It is frequency independent antenna.
- 26. Log-Periodic Antenna (Applications) EMCMEASUREMENT HF COMMUNICATION FOR DIPLOMATIC TRAFFIC
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- 29. HORN ANTENNA • Constructedby Indian radio researcher Jagadish Chandra Bose in 1897. • Transmit radio waves from a waveguide or collect radio waves into a waveguide for reception. • Frequency-range above 300MHz. • Widely used satellite dishes and radio telescopes.
- 30. Horn Antenna (Advantages) •No resonant elements. • Operate over a wide range of frequencies. • Usable bandwidth 1GHz to 20GHz. • Gain ranges upto 25 dB,with 10 -20 dB typical.
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- 33. LOOPANTENNA • Invented byGordon Nelson. • Adirectional-type antenna consisting of one or more complete turns of a conductor. • It determine the direction of arrival of radio signals. • Frequency range – 500-1600KHz. • Types of loop antenna 1. Small LoopAntenna 2. Resonant LoopAntenna
- 34. Loop Antenna (Advantages) •Variety of configurations are possible. • Choose from multiple shapes. • Exhibits the same radiation pattern as a dipole. • Potential gain of up to 2 dB. • Variety of orientations are possible. • Easy to build & inexpensive.
- 35. Loop Antenna (Applications) AMLOOP ANTENNA UHF LOOP ANTENNA
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- 37. PARABOLIC (DISH) ANTENNA •Invented by Heinrich Hertz in 1887. • Functions similarly to a flashlight reflector to direct the radio waves or receive radio waves from one particular direction only. • Highest gains that is, they can produce the narrowest beam widths, of any antenna type. • Used as high-gain antennas for point-to- point communications and radio telescopes.
- 38. Parabolic Antenna (Advantages) •High directivity. • Primary mirror for all the frequencies in the project. • Small irritation loss. • High Gain.
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- 40. Conclusion • Antennas playsan important role in our daily life. • Antenna are used to convert electrical energy to electromagnetic energy. • All the antennas are very useful in all the application such as transmitter and receiver. • It is impossible to transmit or recieve our signal without the use of antenna at the transmitter and receiver ends.