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Antenna system
An antenna converts electric power into radio waves and vice versa. There are two main categories of antennas - omnidirectional antennas that radiate in all directions, and directional antennas that preferentially radiate in a particular direction. Key parameters that define antennas include frequency, directivity, efficiency, gain, wavelength, and polarization. Common types of antennas discussed are Yagi antennas, log-periodic antennas, horn antennas, loop antennas, and parabolic antennas.
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Antenna system
- 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 • ANTENNA EFFICIENCY • ANTENNA GAIN • FRISS TRANSMISSION EQUATION • ANTENNA NOISE TEMPERATURE • WAVELENGTH • POLARIZATION
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- 12. • ANTENNA EFFICIENCY •ANTENNA GAIN
- 13. • FRISS TRANSMIONEQUATION • ANTENNA NOISE TEMPERATURE Ts = Tin + Te
- 14. • WAVELENGTH λ =c / f
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- 16. TYPES OF POLARIZATION • CROSSPOLARIZATIOIN • CIRCULAR POLARIZATION
- 17. TYPES OF ANTENNAS •TRAVELLING WAVE ANTENNAS • LOG-PERIODIC ANTENNAS • APERTURE ANTENNAS • WIRE ANTENNAS • 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 YAGI ANTENNA. • 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. LOOP ANTENNA • Inventedby Gordon Nelson. • A directional-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 Loop Antenna 2. Resonant Loop Antenna
- 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.
Editor's Notes
- #2 The first antennas were built in 1888 by German physicist Heinrich Hertz in his pioneering experiments to prove the existence of electromagnetic waves predicted by the theory of James Clerk Maxwell. Hertz placed dipole antennas at the focal point of parabolic reflectors for both transmitting and receiving.
- #3 Antennas are essential components of all equipment that uses radio. They are used in systems such as : radio broadcasting, broadcast television, two-way radio, communications receivers, radar, cell phones, and satellite communications, as well as other devices such as garage door openers, wireless microphones, Bluetooth-enabled devices, wireless computer networks, baby monitors, and RFID tags on merchandise.
- #4 In transmission, a radio transmitter supplies an electric current to the antenna's terminals, and the antenna radiates the energy from the current as electromagnetic waves (radio waves). In reception, an antenna intercepts some of the power of an electromagnetic wave in order to produce an electric current at its terminals, that is applied to a receiver to be amplified.
- #8 In radio communication, an omnidirectional antenna is a class of antenna which radiates radio wave power uniformly in all directions in one plane, with the radiated power decreasing with elevation angle above or below the plane, dropping to zero on the antenna's axis. Omnidirectional antennas are widely used for radio broadcasting antennas, and in mobile devices that use radio such as cell phones, FM radios, walkie-talkies, wireless computer networks, cordless phones, GPS as well as for base stations that communicate with mobile radios, such as police and taxi dispatchers and aircraft communications.
- #9 A directional antenna or beam antenna is an antenna which radiates or receives greater power in specific directions allowing for increased performance and reduced interference from unwanted sources.
- #10 A directional antenna or beam antenna is an antenna which radiates or receives greater power in specific directions allowing for increased performance and reduced interference from unwanted sources.
- #17 The phenomenon in which waves of light or other radiation are restricted in direction of vibration