# Chapter16 Antennas¶

## Example 16.7.2,Pg.no.590¶

In [1]:
import math
from math import sqrt
g_x=0.5
x=math.asin(sqrt(g_x))
g_y=0.5
y1=math.asin(sqrt(g_y))
y=y1+90
#Therefore
z=y-x
print 'The −3dB beamwidth is',z,'degree'

The −3dB beamwidth is 90.0 degree


## Example 16.9.1,Pg.no.597¶

In [2]:
import math
from math import pi
Io=1
wl=1
phy_length=wl/2
I_av=2*Io/pi
#Thus area is given as
Area=I_av*phy_length
l_eff=wl/pi
l_eff=round(l_eff,2)
#From the above eq l_effective is given as
print 'l_effective=',l_eff

l_effective= 0.32


## Example 16.19.1,Pg.no.621¶

In [3]:
import math
from math import pi
D=6.0        #reflector diameter in m
n=0.65     #illumination effeciency
f=10**10   #frequency of operation in Hz
c=3*10**8  #velo of light in m/s
wl=0.03  #c/f
A=(pi*D**2)/4
A_eff=n*A
A_eff=round(A_eff,2)
print 'Effective area is',A_eff,'m**2'
D0=(4*pi*A_eff)/wl**2
D0=round(D0,1)
print 'The directivity is',D0
BW_dB=70*wl/D
print 'The −3dB beamwidth is',BW_dB,'degree'
BW_null=2*BW_dB
print 'The null beamwidth is',BW_null,'degree'

Effective area is 18.38 m**2
The directivity is 256633.2
The −3dB beamwidth is 0.35 degree
The null beamwidth is 0.7 degree