path: root/Antenna_and_Wave_Propagation_by_k.k._sharma/chapter4.ipynb

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  {
   "cells": [
    {
     "cell_type": "heading",
     "level": 1,
     "metadata": {},
     "source": [
      "chapter 04 : Antenna Arrays"
     ]
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Exa 4.3 : page 4.67"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "from math import acos, pi, cos, sqrt, degrees\n",
      "#given data :\n",
      "from sympy import symbols\n",
      "lamda, Ep = symbols('lamda Ep')\n",
      "d = 3.0/2*lamda\n",
      "beta = 2*pi/lamda\n",
      "delta = 0 # for broad side array\n",
      "theta = pi/2 # for maxima\n",
      "si = 3*pi/2*cos(theta)\n",
      "E0 = Ep/sqrt(2) # at half power beam width\n",
      "#Ep = 2*E0*cos(si/2)\n",
      "#it leads to cos(3*pi/2*cos(theta))=1/sqrt(2)\n",
      "theta=acos(acos(1/sqrt(2))/(3*pi/2))  # radian\n",
      "theta = degrees(theta)  # degree\n",
      "HPBW=2*(90-theta) #in degree\n",
      "print \"(i) HPBW = %0.f degree \" %HPBW \n",
      "# 2nd part is wrong. Some mistake in question as cos(theta) = 13/12 which >1 not possible"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "(i) HPBW = 19 degree \n"
       ]
      }
     ],
     "prompt_number": 18
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Exa 4.4 : page 4.68"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "from math import log10\n",
      "from sympy import symbols\n",
      "lamda = symbols('lamda')\n",
      "#given data :\n",
      "n=10 #no. of elements\n",
      "d=lamda/4 #separation in meter\n",
      "D=2*n/(lamda/d)\n",
      "Ddb=10*log10(D) #in db\n",
      "print \"For broad side array D = %0.2f db \" %Ddb \n",
      "D=4*n/(lamda/d)\n",
      "Ddb=10*log10(D) #in db\n",
      "print \"For end fire array D = %0.2f db \" %Ddb "
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "For broad side array D = 6.99 db \n",
        "For end fire array D = 10.00 db \n"
       ]
      }
     ],
     "prompt_number": 22
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Exa 4.5 : page 4.68"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "from math import sqrt, pi\n",
      "#given data :\n",
      "from sympy import symbols, N\n",
      "lamda = symbols('lamda')\n",
      "delta=-90 #in degree\n",
      "#Formula : HPBW=57.3/(sqrt(L/(2*lambda))) in Degree\n",
      "n=20 #no. of point sources\n",
      "d=lamda/4 #in meter\n",
      "L=(n-1)*d\n",
      "HPBW=57.3/(sqrt(L/lamda/2)) # in Degree\n",
      "print \"HPBW = %0.2f Degree \" %HPBW \n",
      "D=4*L/lamda #Directivity\n",
      "print \"Directivity = %0.2f \" %D \n",
      "Ae = D*lamda**2/4/pi\n",
      "print \"Effective aperture : Ae =\",N(Ae,3)\n",
      "Omega=4*pi/D #in steradian\n",
      "print \"Beam Solid Angle : Omega =\",round(Omega,2),\"Steradian\" \n",
      "#Note : Answer in the book is not accurate."
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "HPBW = 37.18 Degree \n",
        "Directivity = 19.00 \n",
        "Effective aperture : Ae = 1.51*lamda**2\n",
        "Beam Solid Angle : Omega = 0.66 Steradian\n"
       ]
      }
     ],
     "prompt_number": 32
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Exa 4.6 : page 4.69"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "from math import degrees\n",
      "#given data :\n",
      "n=8 #no. of half wave dipoles\n",
      "lamda=100 #in cm\n",
      "lamda=lamda*10**-2 #in m\n",
      "d=50 #in cm\n",
      "d=d*10**-2 #in m\n",
      "I=0.5 #in A\n",
      "Rr=73 #in Ohm\n",
      "Pr=n*I**2*Rr #in Watts\n",
      "print \"Pr = %0.2f Watts \" %Pr \n",
      "BWFN=2*lamda/(n*d) #in radian\n",
      "HPBW=BWFN/2 #in radian\n",
      "print \"HPBW = %0.2f degree\" % degrees(HPBW)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Pr = 146.00 Watts \n",
        "HPBW = 14.32 degree\n"
       ]
      }
     ],
     "prompt_number": 34
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Exa 4.7 : page 4.69"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "from math import log10\n",
      "from sympy import symbols, N\n",
      "lamda = symbols('lamda')\n",
      "#given data :\n",
      "n=10 #no. of elements\n",
      "d=lamda/4 #separation in meter\n",
      "Do=1.789*4*n*d/lamda\n",
      "Dodb=10*log10(Do) #in db\n",
      "print \"Do = %0.2f db\" %(Dodb) "
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Do = 12.53 db\n"
       ]
      }
     ],
     "prompt_number": 36
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Exa 4.13 : page 4.74"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "from math import sin, pi\n",
      "#given data :\n",
      "n=8 #no. of elements\n",
      "BWFN=45 #in degree\n",
      "theta=45 #in degree\n",
      "f=40 #in MHz\n",
      "f=f*10**6 #in Hz\n",
      "#Formula : theta=2*asin(2*pi/(n*dr))\n",
      "dr=(2*pi/n)/sin((theta/2)*(pi/180)) #\n",
      "c=3*10**8 #speed of light in m/s\n",
      "lamda=c/f #in m\n",
      "d=dr*lamda/(2*pi) #in m\n",
      "print \"Distance = %0.2f m \" %d "
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Distance = 2.34 m \n"
       ]
      }
     ],
     "prompt_number": 37
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Exa 4.14 : page 4.74"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "#given data :\n",
      "n=10 #no. of elements\n",
      "from sympy import symbols, N\n",
      "lamda = symbols('lamda')\n",
      "#given : \n",
      "d=lamda/4 #in m\n",
      "Llambda=n*d/lamda\n",
      "D=2*Llambda #in unitless \n",
      "print \"Directivity of broadside uniform array = %0.2f \" %D"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Directivity of broadside uniform array = 5.00 \n"
       ]
      }
     ],
     "prompt_number": 40
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Exa 4.16 : page 4.75"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "from math import pi\n",
      "n=4 \n",
      "from sympy import symbols, N, cos, solve\n",
      "lamda, theta = symbols('lamda theta')\n",
      "d=lamda/2\n",
      "delta = pi/3\n",
      "dr = 2*pi*d/lamda\n",
      "# Peaks\n",
      "si = pi*cos(theta)+pi/3\n",
      "theta = solve(si, theta) # radian\n",
      "theta = degrees(theta[0]) # degree\n",
      "print \"Peaks : theta =\",round(theta,2),\"degree\"\n",
      "# Nulls\n",
      "print \"Nulls : \"\n",
      "for k in range(0,3):\n",
      "    theta = degrees(acos(-1.0/3+k/2.0))\n",
      "    print \"k =\",k,\", theta =\",round(theta,2),\"degree\"\n",
      "print \"Side lobes :\"\n",
      "for k in range(0,3):\n",
      "    theta = degrees(acos(-1.0/3+(2*k+1)/4.0))\n",
      "    print \"k =\",k,\", theta =\",round(theta,2),\"degree\"\n",
      "# Ans in the textbook is not accurate."
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Peaks : theta = 109.47 degree\n",
        "Nulls : \n",
        "k = 0 , theta = 109.47 degree\n",
        "k = 1 , theta = 80.41 degree\n",
        "k = 2 , theta = 48.19 degree\n",
        "Side lobes :\n",
        "k = 0 , theta = 94.78 degree\n",
        "k = 1 , theta = 65.38 degree\n",
        "k = 2 , theta = 23.56 degree\n"
       ]
      }
     ],
     "prompt_number": 74
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Exa 4.17 : page 4.76"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "from math import cos, sin, pi\n",
      "#given data :\n",
      "MainBeamwidth=45 #in degree\n",
      "thetaN=MainBeamwidth/2 #in degree\n",
      "thetaN=thetaN*pi/180 #in radian\n",
      "m=5 #no. of elements\n",
      "#given : d=lambda/2 in meter\n",
      "x=cos(pi/(2*(m-1))) \n",
      "xo=x/cos((pi/2)*sin(thetaN)) #unitless\n",
      "print \"E5=ao*z+a1*(2*z**2-1)+a2*(8*z**4-8*z**2+1)\" \n",
      "print \"We Know that : z=x/xo, E5=T4*xo\" \n",
      "print \"ao=a1*(2*(x/xo)**2-1)+a2*[8*(x/xo)**4-8*(x/xo)**2+1]=8*x**4-8*x**2+1\" \n",
      "print \"By comparing the term we have : \" \n",
      "print \"a2=xo**4  a1=4*a2-4*xo**2  ao=1+a1-a2 \"\n",
      "a2=xo**4 \n",
      "a1=4*a2-4*xo**2 \n",
      "ao=1+a1-a2 \n",
      "print \"And therefore the 5 elements array is given by : \" \n",
      "print (a2),\"  \",(a1),\"  \",(2*ao),\"  \",(a1),\"  \",a2"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "E5=ao*z+a1*(2*z**2-1)+a2*(8*z**4-8*z**2+1)\n",
        "We Know that : z=x/xo, E5=T4*xo\n",
        "ao=a1*(2*(x/xo)**2-1)+a2*[8*(x/xo)**4-8*(x/xo)**2+1]=8*x**4-8*x**2+1\n",
        "By comparing the term we have : \n",
        "a2=xo**4  a1=4*a2-4*xo**2  ao=1+a1-a2 \n",
        "And therefore the 5 elements array is given by : \n",
        "1.5218051188    1.15276185234    1.26191346708    1.15276185234    1.5218051188\n"
       ]
      }
     ],
     "prompt_number": 82
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Exa 4.18 : page 4.77"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "from __future__ import division\n",
      "#given data :\n",
      "#Side lobe level below main lobe\n",
      "print \"Side lobe level below main lobe : \"\n",
      "SideLobe=20 #in dB\n",
      "r=10**(SideLobe/20) #\n",
      "print \"r=\",r  \n",
      "#No. of elements are 5, n=5\n",
      "print \"No. of elements are 5, n=5 :\" \n",
      "print \"Tchebyscheff polynomials of degree (n-1) is\" \n",
      "print \"5-1=4\" \n",
      "print \"T4(xo)=r\" \n",
      "print \"8*xo**4-8*xo**2+1=10\" \n",
      "print \"By using alternate formula, we get\" \n",
      "m=4 \n",
      "r=10 \n",
      "xo=(1/2)*((r+sqrt(r**2-1))**(1/m)+(r-sqrt(r**2-1))**(1/m))\n",
      "print \"xo=\" ,xo\n",
      "print \"E5=T4(xo)\"\n",
      "print \"E5=ao*z+a1*(2*z**2-1)+a2*(8*z**4-8*z**2+1)\" \n",
      "print \"We Know that : z=x/xo, E5=T4*xo\" \n",
      "print \"ao=a1*(2*(x/xo)**2-1)+a2*[8*(x/xo)**4-8*(x/xo)**2+1]=8*x**4-8*x**2+1\" \n",
      "print \"By comparing the term we have : \" \n",
      "print \"a2=xo**4  a1=4*a2-4*xo**2  ao=1+a1-a2 \"\n",
      "a2=xo**4 \n",
      "a1=4*a2-4*xo**2 \n",
      "ao=1+a1-a2 \n",
      "print \"And therefore the 5 elements array is given by : \" \n",
      "print round(a2,3),\"  \",round(a1,3),\"  \",round(2*ao,3),\"  \",round(a1,3),\"  \",round(a2,3)\n",
      "# Ans in the textbook are not accurate."
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Side lobe level below main lobe : \n",
        "r= 10.0\n",
        "No. of elements are 5, n=5 :\n",
        "Tchebyscheff polynomials of degree (n-1) is\n",
        "5-1=4\n",
        "T4(xo)=r\n",
        "8*xo**4-8*xo**2+1=10\n",
        "By using alternate formula, we get\n",
        "xo= 1.29329190052\n",
        "E5=T4(xo)\n",
        "E5=ao*z+a1*(2*z**2-1)+a2*(8*z**4-8*z**2+1)\n",
        "We Know that : z=x/xo, E5=T4*xo\n",
        "ao=a1*(2*(x/xo)**2-1)+a2*[8*(x/xo)**4-8*(x/xo)**2+1]=8*x**4-8*x**2+1\n",
        "By comparing the term we have : \n",
        "a2=xo**4  a1=4*a2-4*xo**2  ao=1+a1-a2 \n",
        "And therefore the 5 elements array is given by : \n",
        "2.798    4.5    5.405    4.5    2.798\n"
       ]
      }
     ],
     "prompt_number": 86
    }
   ],
   "metadata": {}
  }
 ]
}