Chapter14, ground Wave Propagation

Example No. 14.6.1, page : 14-11

In [1]:
from math import log10
d=36000 #km(height of satellite)
f=4000 #MHz(frequency)
GT=20 #dB(Transmitter gain)
GR=40 #dB(Reciever gain)
PT=200 #W(Transmitted power)
PT=10*log10(PT) #dB(Transmitted power)
print "Part (i):" 
Ls=32.44+20*log10(f)+20*log10(d) #dB(Free space transmission loss)
print "\tFree space transmission loss = %0.2f dB "%Ls 
print "Part (ii):" 
PT=200 #W(Transmitted power)
PT_dB=10*log10(PT) #dB(Transmitted power)
PR_dB=PT_dB+GT+GR-Ls #dB(Recieved power)
PR=10**(PR_dB/10) #W(Recieved power)
print "\tReceived power = %0.2f pW  "%(PR*10**12)

Part (i):
	Free space transmission loss = 195.61 dB 
Part (ii):
	Received power = 5.50 pW

Example No. 14.6.2, page : 14-12

In [4]:
from math import log10, sqrt, pi

f=150 #MHz(frequency)
c=3*10**8 #m/s(speed of light)
GT=1.64 #dB(Transmitter gain)
PT=20 #W(Transmitted power)
d=50 #km(distance)
lamda=c/(f*10**6) #m(Wavelength)
E=sqrt(30*GT*PT)/(d*1000) #V/m(emf induced)
le=lamda/pi #m(Effective length)
Voc=E*le #V/m(Open circuit voltage)
print "Open circuit voltage = %0.2f micro Volt "%(Voc*10**6) 

Open circuit voltage = 399.40 micro Volt

Example No. 14.10.1, page : 14-24

In [5]:
from math import log10, sqrt, pi

ht=100 #m(transmitter height)
hr=100 #m(receiver height)
d=3.57*(sqrt(ht)+sqrt(hr)) #km(Range)
print "Range of space wave propagation = %0.2f km "%d 

Range of space wave propagation = 71.40 km

Example No. 14.10.2, page : 14-27

In [6]:
from math import sqrt, pi

ht=100 #feet(transmitter height)
hr=50 #feet(receiver height)
d=1.4142*(sqrt(ht)+sqrt(hr)) #miles(Range)
print "Radio horizon = %0.2f miles "%d 

Radio horizon = 24.14 miles

Example No. 14.10.3, page : 14-28

In [7]:
from math import sqrt
ht=80 #m(transmitter height)
hr=50 #m(receiver height)
d=4.12*(sqrt(ht)+sqrt(hr)) #km(Range)
print "Maximum distance = %0.2f km  "%d 

Maximum distance = 65.98 km

Example No. 14.10.4, page : 14-28

In [8]:
from math import sqrt
ht=100 #m(transmitter height)
d=80 #km(receiver height)
hr=(d/4.12-sqrt(ht))**2 #m(range)
print "Required height of receiving antenna = %0.2f meter "%hr 

Required height of receiving antenna = 88.69 meter

Example No. 14.10.5, page : 14-28

In [9]:
ht=100 #m(transmitter height)
d=4.12*sqrt(ht) #km(Horizon distance)
print "Horizon distance = %0.2f km "%d 

Horizon distance = 41.20 km

Example No. 14.10.6, page : 14-36

In [11]:
from math import sqrt
P=35 #W(Transmitter power
ht=45 #m(transmitter height)
hr=25 #m(receiver height)
f=90 #MHz(frequency)
c=3*10**8 #m/s(Speed of light)
d=4.12*(sqrt(ht)+sqrt(hr)) #km(line of sight distance)
print "Distance of line of sight communication = %0.2f km  "%d 
lamda=c/(f*10**6) #m(Wavelength)
ER=88*sqrt(P)*ht*hr/(lamda*(d*1000)**2) #V/m(Field strength)
print "Field strength = %0.2f micro Volt/meter "%(ER*10**6) 
#Answer is wrong in the textbook.

Distance of line of sight communication = 48.24 km  
Field strength = 83.90 micro Volt/meter