chapter11:Radars

Example 11.1, Page number 504

In [1]:
#calculate maximum range of radar system, maximum range of radar system in nautical miles
import math

#Variable declaraion
lamda = 3.*10**-2#operating unit(cm)
Pt = 600.*10**3  #peak pulse power(W)
Smin = 10.**-13  #minimum detectable signal(W)
Ae = 5.          #m^2
sigma = 20.      #cross sectional area(m^2)

#Calculations
Rmax = ((Pt*Ae**2*sigma)/(4*math.pi*lamda**2*Smin))**0.25
Rmax_nau = Rmax/1.853

#Result
print "The maximum range of radar system is",round((Rmax/1E+3),3),"km"
print "The maximum range of radar system in nautical miles is",round((Rmax_nau/1E+3)),"nm"

The maximum range of radar system is 717.657 km
The maximum range of radar system in nautical miles is 387.0 nm

Example 11.2, Page number 504

In [2]:
#calculate Maximum range possible of the antenna
#Variable declaration
Pt = 250.*10**3  #peak pulse power(W)
Smin = 10.**-14  #minimum detectable signal(W)
Ae = 10.         #m^2
sigma = 2.       #cross sectional area(m^2)
f = 10*10**9     #frequency(Hz)
c = 3*10**8      #velocity of propagation(m/s)
G = 2500         #power gain of antenna

#Calculations
lamda = c/f
Rmax = ((Pt*G*Ae*sigma)/((4*math.pi)**2*Smin))**0.25

#Result
print "Maximum range possible of the antenna is",round((Rmax/1E+3),2),"km"

Maximum range possible of the antenna is 298.28 km

Example 11.3, Page number 504

In [3]:
#calculate sight cross section area
import math

#Variable declaration
Pt = 250.*10**3   #peak pulse power(W)
f = 10.*10**9     #frequency(Hz)
c = 3.*10**8      #velocity of propagation(m/s)
G = 4000          #power gain of antenna
R = 50*10**3      #range(m)
Pr = 10**-11      #minimum detectable signal(W)

#Calculations
lamda = c/f
Ae = (G*lamda**2)/(4*math.pi)
sigma = (Pr*((4*math.pi*R**2)**2))/(Pt*G*Ae)

#Result
print "The radar can sight cross section area of",round(sigma,2),"m^2"

The radar can sight cross section area of 34.45 m^2

Example 11.4, Page number 505

In [4]:
#calculate radar's unambiguous range, duty cycle for radar, average power, Bandwidth range for radar

#Variable declaration
Pt = 400*10**3     #transmitted power(W)
prf = 1500.        #pulse repitiion frequency(pps)
tw = 0.8*10**-6    #pulse width(sec)
c = 3.*10**8       #velocity of propagation(m/s)

#Calculations
#Part a
Run = c/(2*prf)

#Part b
dc = tw/(1/prf)

#Part c
Pav = Pt*dc

#Part d
n1 = 1
BW1 = n1/tw

n2 = 1.4
BW2 = n2/tw

#Results
print "The radar's unambiguous range is",round((Run/1E+3),2),"km"
print "The duty cycle for radar is",dc
print "The average power is",round(Pav,2),"W"
print "Bandwidth range for radar is",(BW1/1E+6),"MHz and",(BW2/1E+6),"MHz"

The radar's unambiguous range is 100.0 km
The duty cycle for radar is 0.0012
The average power is 480.0 W
Bandwidth range for radar is 1.25 MHz and 1.75 MHz

Example 11.5, Page number 505

In [5]:
#calculate maximum detection range 
import math

#Variable declaration
Pt = 2.5*10**6    #power output(W)
D = 5             #antenna diameter(m)
sigma = 1         #cross sectional area of target(m^2)
B = 1.6*10**6     #receiver bandwidth(Hz)
c = 3.*10**8      #velocity of propagation(m/s)
Nf = 12.           #noise figure(dB)
f = 5*10**9       #frequency(Hz)

#Calculations
lamda = c/f
F = 10**(Nf/10)
Rmax = 48*(((Pt*D**4*sigma)/(B*lamda**2*(F-1)))**0.25)

#Result
print "The maximum detection range is",round(Rmax),"km"

The maximum detection range is 558.0 km

Example 11.6, Page number 506

In [6]:
#calculate Maximum range with echoing of 50 times and If transmitter power is doubled, range would increase by a factor of
import math 

#Variable declaration
Rmax = 30   #maximum range of radar(km)
n = 50      #no. of echos

#Calculation
R = Rmax*math.sqrt(math.sqrt(n))

#After doubling the power
R1 = math.sqrt(math.sqrt(2))

#Results
print "Maximum range with echoing of 50 times is",round(R),"km"
print "If transmitter power is doubled, range would increase by a factor of",round(R1,2)

Maximum range with echoing of 50 times is 80.0 km
If transmitter power is doubled, range would increase by a factor of 1.19