Chapter 9: Reflector Antennas

Example 9-2.1, Page number: 372

In [1]:
from math import pi,sqrt

#Variable declaration
P_transmit = 25000.0      #Power transmitted by station transmitter (W)
gain_dbi = 29.0           #Gain of array (dBi)
r = 7500e3                #Distance (m)
h = 250e3                 #Height (m)
z = 377.0                 #Intrinsic impedence of free space (ohm)

gain = 10**(gain_dbi/10)    #Gain of array (unitless)
erp = gain*P_transmit       #Effective radiated power (W)
p_area = erp/(2*pi*r*h)     #power per unit area at distance r (W/m^2)
field_str = sqrt(p_area*z)    #Field strength (mV/m)

print "The effective radiated power is", round(erp,-5),"W"
print "The field strength at the distance r is ",round(field_str,3), "V/m^2"
The effective radiated power is 19900000.0 W
The field strength at the distance r is  0.025 V/m^2