Asked Dec 24, 2019

The radiation pattern of an antenna is given by F(x)= cos4 x with 0<x<pi/2.

What will be the directivity of the antenna?


Expert Answer

Step 1

Directivity is a very important antenna parameter and it can be used to determine how concentrated the radiation is in a specific direction. If antenna radiation pattern F(x) is given, then the directivity can be expressed as


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F(x) --> (1) max D = F(x)av F(x)mx Maximum value of radiation pattern max F(x)n = Average value of radiation pattern ang

Step 2

Radiation pattern is expressed in spherical polar coordinates.

In this case, the radiation pattern is given as


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F(x)=cos* x where 0 <x <

Step 3

The maximum value of F(x) will be 1. The average value of F(x) can be computed in the following way:


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||cos*xsin.xdrdø F(x)mz = ang Let t = cos.x. .. sinxdx = -dt. [[-*a] x 2.7 x [[-t°di] .. F(x)mg 4л avg => F(x) avg 10


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