8.Calculation of receiver antenna gain
1. Antenna diameter Diameter of parabolic reflector antenna is referred as antenna
diameter. It is denoted by ‘D.
2.Antenna
efficiency Antenna efficiency is the ratio of input power to the radiated power
of the antenna. It is denoted by ‘h’.
The value of ‘h’
lice between 0.55 to 0.73.
3.Antenna gain GR The isotropic power gain
of the antenna, GT, is defined as the power density in the maximum
direction, denoted here by PD , to the power density archived by a
100% efficient isotropic radiator.
Thus
GR=PD/(PT/4p)
PT
is the total power radiated.
Antenna gain in GR (dB) =
10 log (p2D2h/(l2*100))
= 10 log (p2D2h/((C/f)2*100))
=10 log (p2D2h/((3/10*f)2*100))
=10
log (p2D2h/(3/f)2)……(dB)……………..[12]
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Example
Calculation
of the gain of a 3.8-m parabolaidal antenna operating frequency of 3.95G
Hz & aperture efficiency
of 0.55
GR=10 log (p2D2h/(3/f)2)
=41.33 dB
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