antenna : The most important part of a wireless network Is a transducer designed to transmit or receive electromagnetic waves Converts electromagnetic waves into electrical currents and vice versa Polarization: Electromagnetic Field = Electric Field + Magnetic Field (90° to each other) It is the way the electro portion of the term electromagnetic (that describes the wave) can move To obtain maximum transmission efficiency, the receive antenna polarization should match that of the transmitted signal to avoid polarization mismatch loss Diversity Is the use of two antennas for each radio to increase the odds that you receive a better signal on either of the antennas as a solution to multipath The isotropic antenna has a perfect spherical radiation pattern Azimuth is horizontal (x-y plane) cross-section of surface (H-Plane) Elevation is vertical (x-z plane) cross-section of surface (E-Plane) Radial distance has a dBi scale Angle corresponds to either longitude (azimuth) or latitude (elevation) Beamwidth is angular width of main lobe at -3 dBi Measured in dBi or dBd (add 2.14 to the dBd gain to be in dBi Gain means concentration of the output power in a certain direction to the input power level By concentrating power in a specific direction, an antenna may generate a net directional gain in power called the antenna gain The gain profile and amplitude will vary depending on the antenna shape and construction shimy
Posted on: Sun, 02 Feb 2014 09:29:03 +0000
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