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diff --git a/Elements_of_Electromagnetics/chapter_13.ipynb b/Elements_of_Electromagnetics/chapter_13.ipynb new file mode 100644 index 00000000..0aaf4534 --- /dev/null +++ b/Elements_of_Electromagnetics/chapter_13.ipynb @@ -0,0 +1,428 @@ +{
+ "metadata": {
+ "name": "chapter_13.ipynb"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+ {
+ "cells": [
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "<h1>Chapter 13: Antennas<h1>"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "<h3>Example 13.1, Page number: 601<h3>"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "'''\n",
+ "A magnetic field strength of 5 muA/m is required at a point on theta = pi/2,\n",
+ "2 km from an antenna in air. Neglecting ohmic loss, how much power must \n",
+ "the antenna transmit if it is \n",
+ "\n",
+ "(a) A Hertzian dipole of length lambda/25?\n",
+ "(b) A half-wave dipole? \n",
+ "(c) A quarter-wave monopole? \n",
+ "(d) A 10-turn loop antenna of radius Po = lambda/20? '''\n",
+ "\n",
+ "import scipy\n",
+ "\n",
+ "#Variable Declaration\n",
+ "\n",
+ "H=5*10**-6 #magnetic field strentgh in A/m\n",
+ "theta=scipy.pi/2 \n",
+ "r=2*10**3 #distance in m\n",
+ "Bdl=2*scipy.pi/25\n",
+ "N=10 #number of turns\n",
+ "\n",
+ "#Calculations\n",
+ "\n",
+ "Ia=4*scipy.pi*r*H/(Bdl*scipy.sin(theta)) #current for part (a) in A\n",
+ "Pa=40*scipy.pi**2*(1/25.0)**2*Ia**2 #power for part (a) in W\n",
+ "def pow(Io,Rrad):\n",
+ " P=0.5*Io**2*Rrad\n",
+ " print round(P*10**3,0),'mW'\n",
+ "\n",
+ "denom=scipy.cos(scipy.pi*scipy.cos(theta)/2) \n",
+ "Ib=H*2*scipy.pi*r*scipy.sin(theta)/denom #current for part (b) in A\n",
+ "Rradb=73 #wave impedance in ohms for (b)\n",
+ "Ic=Ib #current for part (c) in A\n",
+ "Rradc=36.56 #wave impedance in ohms for (c)\n",
+ "Id=H*r*400/(10*scipy.pi**2) #current for part (d) in A\n",
+ "Rradd=320*scipy.pi**6*N**2/20**4 #wave impedance in ohms for (d)\n",
+ "\n",
+ "#Results\n",
+ "\n",
+ "print 'The power transmitted in mW if antenna is ;'\n",
+ "print '(a) A Hertzian dipole of length lambda/25 =','\\n',round(Pa*10**3,0),'mW'\n",
+ "print '(b) A half-wave dipole ='\n",
+ "pow(Ib,Rradb)\n",
+ "print '(c) A quarter-wave monopole ='\n",
+ "pow(Ic,Rradc)\n",
+ "print '(d) A 10-turn loop antenna of radius Po = lambda/20 ='\n",
+ "pow(Id,Rradd)"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "The power transmitted in mW if antenna is ;\n",
+ "(a) A Hertzian dipole of length lambda/25 = \n",
+ "158.0 mW\n",
+ "(b) A half-wave dipole =\n",
+ "144.0 mW\n",
+ "(c) A quarter-wave monopole =\n",
+ "72.0 mW\n",
+ "(d) A 10-turn loop antenna of radius Po = lambda/20 =\n",
+ "158.0 mW\n"
+ ]
+ }
+ ],
+ "prompt_number": 2
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "<h3>Example 13.2, Page number: 603<h3>"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "'''\n",
+ "An electric field strength of 10 micro V/m is to be measured at an observation \n",
+ "point theta=pi/2, 500 km from a half-wave (resonant) dipole antenna operating\n",
+ "in air at 50 MHz. \n",
+ "(a) What is the length of the dipole? \n",
+ "(b) Calculate the current that must be fed to the antenna. \n",
+ "(c) Find the average power radiated by the antenna. \n",
+ "(d) If a transmission line with Zo = 75 ohms is connected to the antenna,\n",
+ "determine the standing wave ratio. '''\n",
+ "\n",
+ "import scipy\n",
+ "import cmath\n",
+ "from numpy import *\n",
+ "\n",
+ "#Variable Declaration\n",
+ "\n",
+ "c=3*10**8 #speed of wave in m/s\n",
+ "f=50*10**6 #frequency in Hz\n",
+ "E=10*10**-6 #field strength in V/m\n",
+ "theta=scipy.pi/2\n",
+ "r=500*10**3 #distance in m\n",
+ "eta=120*scipy.pi #wave impedance in ohms\n",
+ "Rrad=73 #in ohms\n",
+ "Zo=75 #in ohms\n",
+ "Zl=73+42.5j\n",
+ "\n",
+ "#Calculations\n",
+ "\n",
+ "l=c/(2*f)\n",
+ "I=E*2*r*scipy.pi*sin(theta)/(eta*(cos((scipy.pi/2)*cos(theta))))\n",
+ "P=0.5*I**2*Rrad\n",
+ "T=(Zl-Zo)/(Zl+Zo)\n",
+ "s=(1+abs(T))/(1-abs(T))\n",
+ "\n",
+ "#Results\n",
+ "\n",
+ "print 'The length of the dipole =',l,'m'\n",
+ "print 'The current that must be fed to the antenna =',round(I*10**3,2),'mA'\n",
+ "print 'The average power radiated by the antenna =',round(P*10**3,1),'mW'\n",
+ "print 'The standing wave ratio =',round(s,4)"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "The length of the dipole = 3 m\n",
+ "The current that must be fed to the antenna = 83.33 mA\n",
+ "The average power radiated by the antenna = 253.5 mW\n",
+ "The standing wave ratio = 1.7636\n"
+ ]
+ }
+ ],
+ "prompt_number": 3
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "<h3>Example 13.4, Page number: 610<h3>"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "'''\n",
+ "Determine the electric field intensity at a distance of 10 km from an antenna \n",
+ "having a directive gain of 5 dB and radiating a total power of 20 kW. '''\n",
+ "\n",
+ "import scipy\n",
+ "\n",
+ "#Variable Declaration\n",
+ "\n",
+ "G=5\n",
+ "r=10*10**3 #in m\n",
+ "P=20*10**3 #power in W\n",
+ "n=120*scipy.pi #wave impedance in ohms\n",
+ "\n",
+ "#Calculations\n",
+ "\n",
+ "Gd=10**(G/10.0)\n",
+ "E=scipy.sqrt(n*Gd*P/(2*scipy.pi*r*r)) #field intensity in V/m\n",
+ "\n",
+ "#Result\n",
+ "\n",
+ "print 'electric field intensity =',round(E,4),'V/m'"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "electric field intensity = 0.1948 V/m\n"
+ ]
+ }
+ ],
+ "prompt_number": 4
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "<h3>Example 13.5, Page number: 611<h3>"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "'''\n",
+ "The radiation intensity of a certain antenna is \n",
+ "\n",
+ "U(theta,phi) = 2sin(theta) sin^3(phi) , 0<theta<pi,0<phi<pi\n",
+ " = 0, elsewhere\n",
+ "\n",
+ "Determine the directivity of the antenna. '''\n",
+ "\n",
+ "import scipy\n",
+ "import scipy.integrate\n",
+ "\n",
+ "#Variable Declaration\n",
+ "\n",
+ "Umax=2.0\n",
+ "\n",
+ "def U(phi,theta):\n",
+ " s=2*scipy.sin(theta)*(scipy.sin(phi))**3/(4.0*scipy.pi)\n",
+ " return s\n",
+ " \n",
+ "#Calculations\n",
+ "\n",
+ "if __name__ == '__main__':\n",
+ " \n",
+ " Uav,er=scipy.integrate.dblquad(lambda theta,phi:U(phi,theta)*scipy.sin(theta), \n",
+ " 0, scipy.pi, lambda theta: 0, lambda theta: scipy.pi)\n",
+ "\n",
+ "D=Umax/Uav #Directivity\n",
+ "\n",
+ "#Result\n",
+ "\n",
+ "print 'directivity of the antenna =',D"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "directivity of the antenna = 6.0\n"
+ ]
+ }
+ ],
+ "prompt_number": 5
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "<h3>Example 13.8, Page number: 624<h3>"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "'''\n",
+ "Find the maximum effective area of a lamba/2 wire dipole operating at 30 MHz.\n",
+ "How much power is received with an incident plane wave of strength 2 mV/m.'''\n",
+ "\n",
+ "import scipy\n",
+ "\n",
+ "#Variable Declaration\n",
+ "\n",
+ "c=3*10**8 #speed of wave in m/s\n",
+ "f=30*10**6 #frequency in Hz\n",
+ "E=2*10**-3 #field strength in V/m\n",
+ "n=120*scipy.pi\n",
+ "R=73 \n",
+ "\n",
+ "#Calculations\n",
+ "\n",
+ "l=c/f #wavelength in m\n",
+ "Gdmax=round(n/(scipy.pi*R),2) \n",
+ "Amax=(l**2/(4*scipy.pi))*Gdmax #maximum effective area in m^2\n",
+ "Pr=(E*E*Amax)/(2*n) #power received in W\n",
+ "\n",
+ "#Results\n",
+ "\n",
+ "print 'maximum effective area =',round(Amax,2),'m^2'\n",
+ "print 'power received =',round(Pr*10**9,2),'nW'"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "maximum effective area = 13.05 m^2\n",
+ "power received = 69.24 nW\n"
+ ]
+ }
+ ],
+ "prompt_number": 6
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "<h3>Example 13.9, Page number: 624<h3>"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "'''\n",
+ "The transmitting and receiving antennas are separated by a distance of \n",
+ "200 lambda and have directive gains of 25 and 18 dB, respectively. If 5 mW\n",
+ "of power is to be received, calculate the minimum transmitted power. '''\n",
+ "\n",
+ "import scipy\n",
+ "\n",
+ "#Variable Declaration\n",
+ "\n",
+ "Gt=25 #in dB\n",
+ "Gr=18 #in dB\n",
+ "r=200 #in units of lambda\n",
+ "Pr=5*10**-3 #power received in W\n",
+ "\n",
+ "#Calculations\n",
+ "\n",
+ "Gdt=10**(Gt/10.0) \n",
+ "Gdr=10**(Gr/10.0)\n",
+ "Pt=Pr*(4*scipy.pi*r)**2/(Gdr*Gdt)\n",
+ "\n",
+ "#Result\n",
+ "\n",
+ "print 'minimum transmitted power =',round(Pt,3),'W'"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "minimum transmitted power = 1.583 W\n"
+ ]
+ }
+ ],
+ "prompt_number": 7
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "<h3>Example 13.10, Page number: 627<h3>"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "collapsed": false,
+ "input": [
+ "'''\n",
+ "An S-band radar transmitting at 3 GHz radiates 200 kW. Determine the signal\n",
+ "power density at ranges 100 and 400 nautical miles if the effective area of \n",
+ "the radar antenna is 9 m^2 . With a 20-m^2 target at 300 nautical miles, \n",
+ "calculate the power of the reflected signal at the radar. '''\n",
+ "\n",
+ "import scipy\n",
+ "\n",
+ "#Variable Declaration\n",
+ "\n",
+ "c=3*(10)**8 #speed of wave in m/s\n",
+ "f=3.0*(10)**9 #frequency in Hz\n",
+ "Aet=9 #effective area in m^2\n",
+ "r1=1.852*(10)**5 #distance in m\n",
+ "r2=4*r1 #distance in m\n",
+ "r3=5.556*10**5 #distance in m\n",
+ "Pr=200*(10)**3 #in W\n",
+ "a=20 #target area in m^2\n",
+ "\n",
+ "#Calculations\n",
+ "\n",
+ "l=c/f #wavelength in m\n",
+ "Gdt=4*scipy.pi*Aet/(l*l)\n",
+ "P1=Gdt*Pr/(4*scipy.pi*r1*r1) #power at 100 nmiles in W/m^2\n",
+ "P2=Gdt*Pr/(4*scipy.pi*r2*r2) #power at 400 nmiles in W/m^2\n",
+ "Pr=Aet*a*Gdt*Pr/(4*scipy.pi*r3*r3)**2 #power of reflected signal in W\n",
+ "\n",
+ "#Results\n",
+ "\n",
+ "print 'Signal power density at 100 nautical miles =',round(P1*1000,3),'mW/m^2'\n",
+ "print 'Signal power density at 400 nautical miles =',round(P2*1000,3),'mW/m^2'\n",
+ "print 'Power of reflected signal =',round(Pr*10**12,5),'pico W'"
+ ],
+ "language": "python",
+ "metadata": {},
+ "outputs": [
+ {
+ "output_type": "stream",
+ "stream": "stdout",
+ "text": [
+ "Signal power density at 100 nautical miles = 5.248 mW/m^2\n",
+ "Signal power density at 400 nautical miles = 0.328 mW/m^2\n",
+ "Power of reflected signal = 0.02706 pico W\n"
+ ]
+ }
+ ],
+ "prompt_number": 8
+ }
+ ],
+ "metadata": {}
+ }
+ ]
+}
\ No newline at end of file |