Describing and comparing antennas through radiation patterns with home construction techniques CS 556 Mobile Communications Fall 2008 Timothy John Adams Introduction Antennas used for mobile communications and other applications ID: 164889
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Slide1
Mobile Communications and Antennas
Describing and comparing antennas through radiation patterns with home construction techniques
CS 556 Mobile Communications
Fall 2008
Timothy John AdamsSlide2
Introduction
Antennas used for mobile communications and other applicationsBasic theory behind antennas and gainComparison of antenna gain using radiation pattern graphs
Uses of antennas
Homemade antennasSlide3
Basic information for antennas
What is an antennaAntennas are conductorsElectric current in the conductor
Electromagnetic fields
Radiated power
Isotropic antennaSlide4
Isotropic power
Spherical pattern representing the power radiated from an isotropic antennaSlide5
Antenna Gain
Isotropic power levelDirected powerHalf-wave dipole antenna power
The decibel
Ratio of power is gain
Gain of isotropic antenna is 1 or 0 dBi
Gain of dipole antenna is 1.64 or 2.15 dBiSlide6
Half-wave dipole
Radiation pattern of a center-fed half-wave dipole antennaSlide7
Omni-directional antennas
Half-wave dipoleQuarter-wave monopoleRadiation pattern characteristicsSlide8
Omni-directional radiation pattern in the horizontal plane
Horizontal plan of radiation pattern for half-wave dipole, as if looking down on the antenna from aboveSlide9
Different elevations but still omni-directional
Half-wave dipole pattern
Quarter-wave monopole patternSlide10
Directional Antennas
Yagi-UdaHornParabolicHelicalSlide11
Yagi-Uda
14 element Yagi-Uda AntennaSlide12
Horn
50 foot horn antenna can pick up weak background radiation from spaceSlide13
Parabolic
Large parabolic antenna
, actually the biggest facility for satellite communication in the world, based in
Raisting
, Bavaria, Germany.Slide14
Helical
Homemade helical antennaSlide15
Radiation patterns
Omni-directionalDirectionalSlide16
Directional radiation pattern
Directed gain from a Yagi-Uda antennaSlide17
Directional radiation pattern
More complex pattern from rhombic (wire) antennaSlide18
Coverage area from directional antenna
Coverage area from rhombic (wire) antennaSlide19
Uses of antennas
Omni-directionalMobile ReceiversBase Stations
Directional
Confined Spaces
To Prevent InterferenceSlide20
Homemade Antennas
Quarter-wave monopoleQuarter-wave monopole with waveguide8-segment Coaxial/Collinear (COCO)Slide21
N-female chassis mounted connector
Basic connector for most homemade antennasSlide22
Quarter-wave monopole antenna with ground plane
Quarter-wave monopoleSlide23
Quarter-wave monopole with waveguide
Basic “
cantenna
”Slide24
Quarter-wave monopole with waveguide and funnel feed
Funnel increases reception capabilitiesSlide25
8-segment Coaxial/Collinear antenna
Uses basic coaxial cableSlide26
Concluding Remarks