Chapter 15 : Introduction to Antennas

Example 15.2 Page No : 500

In [2]:
# Variables
c = 3.*10**8;  #speed of light
f = 2.*10**9;   #frequency

# Calculations and Results
lembda = c/f;   #wavelength
print 'The wavelength of 2GHz is,  =  %.2f m'%(lembda);
D = 15.;  #m
Rff = 2*D**2/lembda;
print ' The distance to the far field is, Rff  =  %i m'%(Rff);

The wavelength of 2GHz is,  =  0.15 m
 The distance to the far field is, Rff  =  3000 m

Example 15.3 Page No : 502

In [4]:
import math
# Variables
Gmax = 10**5;

# Calculations
Gmax_dB = 10*math.log10(Gmax);

# Results
print 'Gmax, dB =  %i dB'%(Gmax_dB);

Gmax, dB =  50 dB

Example 15.4 Page No : 504

In [6]:
import math 

# Variables
d = 10.**5;  #m
Pt = 100.;  #W

# Calculations
Pd = Pt/(4*math.pi*d**2);

# Results
print 'The power density is ,Pd =  %.1f pW/m**2'%(Pd*10**12);

The power density is ,Pd =  795.8 pW/m**2

Example 15.5 Page No : 504

In [7]:
import math 

# Variables
d = 10.**5;  #m
Pt = 100.;  #W
Gt = 50;

# Calculations
Pd = Gt*Pt/(4*math.pi*d**2);

# Results
print 'The power density is ,Pd =  %.2f nW/m**2'%(Pd*10**9);

The power density is ,Pd =  39.79 nW/m**2

Example 15.6 Page No : 504

In [8]:
import math 

# Variables
c = 3.*10**8;  #speed of light
f = 15.*10**9;   #frequency

# Calculations and Results
lembda = c/f;   #wavelength
print 'The wavelength of 15 GHz is,  =  %.2f m'%(lembda);

d = 41.*10**6;  #m
Pt = 50.;  #W
Gt = 10.**4;
Gr = 10.**5
Pr = lembda**2*Gr*Gt*Pt/((4*math.pi)**2*d**2);
print 'The power density is , Pr =  %.1f pW'%(Pr*10**12);

The wavelength of 15 GHz is,  =  0.02 m
The power density is , Pr =  75.3 pW

Example 15.7 Page No : 506

In [10]:
# Variables
Pt = 2000.;  #W
Irms = 5.;

# Calculations
Rrad = Pt/Irms**2;

# Results
print 'The radiation resistance is , Rrad =  %i ohm'%(Rrad);

The radiation resistance is , Rrad =  80 ohm

Example 15.11 Page No : 511

In [11]:
import math 
# Variables
#misprinted example number
c = 3.*10**8;  #speed of light
f = 10.*10**9;   #frequency

# Calculations and Results
lembda = c/f;   #wavelength
print 'The wavelength of 2GHz is,  =  %.2f m'%(lembda);
D = 12;  #m
Ap = math.pi*D**2/4;
print ' a)The physical area is ,Ap =  %.2f m**2  '%(Ap);
n1 = .7;   #efficiency
Ae = n1*Ap;
print '  The effective capture area is ,Ae =  %.2f m**2'%(Ae);
G = 4*math.pi*Ae/lembda**2;
print ' b) The gain is ,G =  %i'%(G);
GdB = 10*math.log10(G);
print ' The gaindB) is , GdB =  %.1f dB'%(GdB);
theta_3dB = 70*lembda/D;
print ' c) The 3 dB beamwidth  =  %.3f degrees'%(theta_3dB);

The wavelength of 2GHz is,  =  0.03 m
 a)The physical area is ,Ap =  113.10 m**2  
  The effective capture area is ,Ae =  79.17 m**2
 b) The gain is ,G =  1105395
 The gaindB) is , GdB =  60.4 dB
 c) The 3 dB beamwidth  =  0.175 degrees

Example 15.12 Page No : 507

In [13]:
# Variables
c = 3.*10**8;  #speed of light
f = 100.*10**6;   #frequency

# Calculations and Results
lembda = c/f;   #wavelength
print 'The wavelength of 2GHz is,  =  %i m'%(lembda);
Ac = 0.13*lembda**2;
print 'The capture area is , Ac =  %.2f m**2'%(Ac);

The wavelength of 2GHz is,  =  3 m
The capture area is , Ac =  1.17 m**2