Chapter 14 Antennas

Example 14.1 Page no 669

In [2]:
#given
c=3*10**8                   #m/s , speed of light              
f=150*10**6                 #frequency

#calculation
h=c/f
x=1/2.0                     #antennas dimension(D)
D=0.5*2
Rff=5*D
h=c/f 
D = h/2

#result
print" distance =",Rff,"m"

 distance = 5.0 m

Example 14.2 Page no 669

In [3]:
#given
c=3*10**8       #velocity of light
f=12.0*10**9    #frequency
D=4.5           #diameter of parabolic reflector

#calculation
h=c/f           #wavelength
x=D/h
R=(2*D**2)/h

#result
print"distance from parabolic reflector= ",R,"m"

distance from parabolic reflector=  1620.0 m

Example 14.3 Page no 671

In [2]:
#given
Pt=10                   #transmitted power
#dipoles have gain 2.15dB  
Gr=1.64
c=3*10**8               #velocity of light
f=144.0*10**6           #frequency
d=50*10**3              #distance between antennas
Gt=1.64                 #recieving antenna gain(ratio) compared to isotropic radiator

#calculation
import math
Pr=Pt*Gt*Gr*(c/f)**2/((16*(math.pi)**2)*(d**2))                #power recieved

#result
print"Power received = ",round(Pr,12),"w"

Power received =  2.96e-10 w

Example 14.4 Page no 674

In [1]:
#Given
c=3*10**8         #velocity of light
f=100*10**6       #frequency

#Calculation
h=c/f         #wavelength
x=h/2.0         #dipole i.e h/2
l=0.95*x       #applying 95% correction,the actual optimum physical length
L=486/100.0      #alternative method to find length

#Result
print"length of antenna = ",l,"m"

length of antenna =  1.425 m