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How to calculate gain from radiation pattern?

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cakalhunter

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Can anybody explain how i can compute gain from radiation pattern? I could not obtain a satisfactory solution for this problem.

Thanks in advance
 

g86

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cakalhunter said:
Can anybody explain how i can compute gain from radiation pattern? I could not obtain a satisfactory solution for this problem.

Thanks in advance

Measure Half power beam width in the E-plane and H-plane. Multiply them and invert and again multiply with 4*pi. The result will be approximate far field directivity. Now multiply directivity with efficiency to calculate Gain. Efficiency is anoter parameter that you have to know.

:!::idea::?:
 

plasma

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and the attachment
 

cakalhunter

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My friend, thanks for your help

but is there a way to obtain gain from radiation pattern? All i have is a radiation pattern.

regards
 

plasma

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If you have AZ and EL pattern take -3dB beam width for example

θaz=20° and θel=25° Assuming efficiency 60% we get k=30000

Gain=30000/20*25=60 ----> transform to dB Gain[dB]=10*log60=17.18dB

read pages 497 and 498 in Attachment

PL
 

Darren_pan

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As plasma mentioned,the method is one shortcut to calculate the Gain,but it is for directivity,and not very accurate.
 

dowjones

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Hello,

if you have the complete pattern (full theta-phi measurement) you can get the directivity to high accuracy, however you will not have efficiency and therefore no gain info.

To get the gain you need to know the ohmic losses of the antenna (conductor and dielectric loss) , or at least a good estimate. In case you know or assume a low loss antenna, then directivity equals the gain.

regards
 

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