# Chapter 3: The Antenna Family

### Example 3-3.2, Page number: 58

In :
#Variable declaration
Z_0 = 377   #Intrinsic impedence of free space(ohm)
Z_d = 710 +0j   #Terminal impedence of dipole cylinder (ohm)

#Calculation
Z_s = (Z_0**2)/(4*Z_d)  #Terminal impedence of the slot (ohm)

#Result
print "The terminal impedence of the slot is", round(Z_s.real), "ohms"

The terminal impedence of the slot is 50.0 ohms


### Example 3-6.1, Page number: 61

In :
import math

#Variable declaration
L = 10              #Horn length (lambda)
delta = 0.25        #Path length difference (lambda)

#Calculation
theta = 2*math.acos(L/(L+delta))    #Horn flare angle (radians)
theta = theta*180/math.pi           #Horn flare angle (degrees)

#Result
print "The largest flare angle for given delta is",round(theta,1), "degrees"

The largest flare angle for given delta is 25.4 degrees


### Example 3-7.1, Page number: 62

In :
import math

#Variable declaration
f = 599e6     #Frequency of TV Station (Hz)
E = 1e-6      #Field strength (V/m)
D = 20        #Diameter of antenna (m)
c = 3e8       #Speed of light (m/s)
Z_0 = 377     #Intrinsic impedence of free space (ohm)

#Calculation
wave_lt = c/f                       #Wavelength (m)
A_e = (D*(wave_lt**2))/(4*math.pi)  #Effective aperture (m^2)
P_r = (E**2)*A_e/Z_0                #Received power (W)

#Result
print "The received power is", round(P_r,17), "W"

The received power is 1.06e-15 W


### Example 3-11.1, Page number: 66

In :
import math

#Variable declaration
n = 4               #Number of patch antennas (lambda)
diameter = 0.5      #diameter of patch antennas (lambda)

#Calculation
A_e = n*diameter            #Effective aperture (lambda^2)
D = (4*math.pi*A_e)         #Directivity (unitless)
D_dbi = 10*math.log10(D)    #Directivity (dBi)
ohm_a = (4*math.pi)/D       #Beam area (steradians)

#Result
print "The directivity is", round(D), "or", round(D_dbi), "dBi"
print "The beam area is", ohm_a, "sr"

The directivity is 25.0 or 14.0 dBi
The beam area is 0.5 sr