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→Directivity
=== Directivity ===
[[File:IsotropicIsotropic3.jpg|thumbgif|200pxleft|frame|Isotropic. Image reproduced from [https://commons.wikimedia.org/wiki/File:Isotropic_radiator_animation_240x240x8frame_0.4sec.gif here]]]
[[File:Omni.jpg|thumb|frame|200px|Omnidirectional]]
[[File:Directional.png|thumb|frame|200px|Directional]]
Based upon directivity, antennas can be divided in three groups:
* '''Isotropic:''' An isotropic antenna is an ideal antenna which radiates uniform power in all directions. Hence its directivity would be 1(0 dB). It's radiation pattern is a sphere.* '''Omnidirectional:''' Omnidirectional antenna radiates uniform power in planes described by a single normal i.e. in any plane and its perpendicular to a normal, the radiation power diminishes as we go away from the planewould be equal in all directions. Hence its the radiation pattern for a simple omnidirectional antenna resembles a “doughnut”as shown in the figure. But it's pattern can also be complex like this figure.
* '''Directional:''' Directional antennas can radiate greater amount of power in a specific direction compared to any other direction. Their directivities are very high. They have complicated (and often interesting) radiation patterns.
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