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antennasystem-190928171019.pptx

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antennasystem-190928171019.pptx

  1. 1. Antenna In radio and electronics, 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.
  2. 2. Antenna
  3. 3. Categories
  4. 4. Antenna According to their applications and technology available, antennas generally fall in one of two categories: 1. Omnidirectional 2. Directional
  5. 5. Omnidirectional Antenna
  6. 6. Omnidirectional Antenna only weakly directional 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.
  7. 7. Directional Antenna
  8. 8. Directional Antenna Directional or beam antennas which are intended to preferentially radiate or receive in a particular direction or directional pattern.
  9. 9. FUNDAMENTAL PARAMETERS OF ANTENNAS • FREQUENCY • DIRECTIVITY • ANTENNAEFFICIENCY • ANTENNAGAIN • FRISS TRANSMISSION EQUATION • ANTENNANOISE TEMPERA TURE • WAVELENGTH • POLARIZATION
  10. 10. • FREQUENCY • DIRECTIVITY
  11. 11. • ANTENNAEFFICIENCY • ANTENNA GAIN
  12. 12. • FRISS TRANSMION EQUATION • ANTENNANOISE TEMPERA TURE Ts = Tin + Te
  13. 13. • W A VELENGTH λ = c / f
  14. 14. • Polarization
  15. 15. TYPES OF POLARIZATION • CROSS POLARIZATIOIN • CIRCULAR POLARIZATION
  16. 16. TYPES OFANTENNAS • TRA VELLING W A VE ANTENNAS • LOG-PERIODIC ANTENNAS • APERTUREANTENNAS • WIREANTENNAS • REFLECTOR ANTENNAS
  17. 17. TRAVELLING WAVE ANTENNAS HELIX ANTENNA YAGI-UDA ANTENNA SPIRAL ANTENNA
  18. 18. Yagi Antenna • Invented by Shintaro Uda in 1926. • Consist of reflector, director and driven element. • It is unidirectional antenna. • High gain > 10 dB • Frequency range – 3MHz-3GHz
  19. 19. 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.
  20. 20. Yagi Antenna (Applications) World War -II Messerschmitt 1110 fighter aircraft Rooftop television
  21. 21. LOG-PERIODIC ANTENNAS BOW TIE ANTENNA LOG-PERIODIC ANTENNA LOG-PERIODIC DIPOLE ANTENNA
  22. 22. LOG-PERIODIC ANTENNAS
  23. 23. Log-Periodic Antenna • Invented by 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.
  24. 24. Log-Periodic Antenna (Advantages) • It is broadband antenna. • It is unidirectional antenna. • It is frequency independent antenna.
  25. 25. Log-Periodic Antenna (Applications) EMC MEASUREMENT HF COMMUNICATION FOR DIPLOMATIC TRAFFIC
  26. 26. APERTURE ANTENNAS SLOTTED WAVEGUIDE ANTENNA SLOT ANTENNA HORN ANTENNA
  27. 27. HORN ANTENNA
  28. 28. HORN ANTENNA • Constructed by 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.
  29. 29. 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.
  30. 30. Horn Antenna (Applications) MICROWAVE RADIOMETER RADAR GUN
  31. 31. WIRE ANTENNAS LOOPANTENNA CLOVER-LEAF ANTENNA HALF-WAVE DIPOLEANTENNA
  32. 32. LOOPANTENNA • Invented by Gordon 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
  33. 33. 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.
  34. 34. Loop Antenna (Applications) AM LOOP ANTENNA UHF LOOP ANTENNA
  35. 35. REFLECTOR ANTENNAS CORNER REFLECTOR ANTENNA PARBOLIC ANTENNA
  36. 36. 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.
  37. 37. Parabolic Antenna (Advantages) • High directivity. • Primary mirror for all the frequencies in the project. • Small irritation loss. • High Gain.
  38. 38. Parabolic Antenna (Applications) RADIO TELESCOPES RADAR ANTENNAS
  39. 39. Conclusion • Antennas plays an 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.

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