{ "metadata": { "name": "" }, "nbformat": 3, "nbformat_minor": 0, "worksheets": [ { "cells": [ { "cell_type": "markdown", "metadata": {}, "source": [ "

Chapter 7: Loop, Slot and Horn Antennas

" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "

Example 7-8.1, Page number: 256

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from math import sqrt,pi,sin,log10\n", "\n", "#Variable declaration\n", "C_lambda = 0.1*pi #Circumference (lambda)\n", "R_m = 1.6 #Mutual resistance of two loops (ohm)\n", "theta1 = 90*pi/180 #Angle of radiation (radians)\n", "theta2 = 2*pi/10 #Angle of radiation (radians)\n", "\n", "#Calculation\n", "Rr = 197*(C_lambda)**4 #Self resistance of loop (ohm)\n", "D1 = (1.5)*(sin(theta1))**2 #Direcivity of loop alone (unitless)\n", "D1_db = 10*log10(D1) #Directivity of loop alone (dBi)\n", "D2 = 1.5*(2*sqrt(Rr/(Rr-R_m))*sin(theta2))**2\n", " #Directivity of loop with ground plane (unitless)\n", "D2_db = 10*log10(D2) #Direcitivy of loop with ground plane (dBi)\n", "\n", "#Result\n", "print \"The directivity of loop alone is %.2f or %.2f dBi\" % (D1,D1_db)\n", "print \"\"\"The direcitivy of loop with ground plane is %.2f or %.0f dBi\n", " \"\"\" %(D2,D2_db)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The directivity of loop alone is 1.50 or 1.76 dBi\n", "The direcitivy of loop with ground plane is 12.47 or 11 dBi\n", " \n" ] } ], "prompt_number": 1 }, { "cell_type": "markdown", "metadata": {}, "source": [ "

Example 7-8.2, Page number:257

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from math import sqrt, sin, pi, log10\n", "\n", "#Variable declaration\n", "Rr = 197.0 #self resistance of loop (ohm)\n", "Rm = 157.0 #mutual resistance of two loops (ohm)\n", "theta = 2*pi/10 #Angle of radiation (radians)\n", "\n", "#Calculation\n", "D = 1.5*(2*sqrt(Rr/(Rr-Rm))*sin(theta))**2 #Directivity (unitless)\n", "D_db = 10*log10(D) #Directivity (dBi)\n", "\n", "#Result\n", "print \"The direcitivy is %.1f or %.1f dBi\" % (D,D_db)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The direcitivy is 10.2 or 10.1 dBi\n" ] } ], "prompt_number": 2 }, { "cell_type": "markdown", "metadata": {}, "source": [ "

Example 7-11.1, Page number: 261

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from math import pi, log10\n", "\n", "#Variable declaration\n", "c = pi #Circumference (m)\n", "f1 = 1 #Frequency (MHz)\n", "f2 = 10 #Frequency (MHz)\n", "d = 10e-3 #Diameter of copper wire (m)\n", "\n", "#Calcalation\n", "RL_Rr1 = 3430/((c**3)*(f1**3.5)*d) \n", "RL_Rr2 = 3430/((c**3)*(f2**3.5)*d)\n", " #Ratio of Loss resistance and radiation resistance (unitless\n", " \n", "k1 = 1/(1+RL_Rr1) #Radiation efficiency (unitless)\n", "k_db1 = 10*log10(k1) #Radiation efficiency (in dB)\n", "k2 = 1/(1+RL_Rr2) #Radiation efficiency (unitless)\n", "k_db2 = 10*log10(k2) #Radiation efficiency (in dB)\n", "\n", "#Result\n", "print \"The radiation effiency for 1 MHz is %.1ef or %.1f dB\" % (k1, k_db1)\n", "print \"The radiation effiency for 10 MHz is %.2f or %.1f dB\" % (k2, k_db2)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The radiation effiency for 1 MHz is 9.0e-05f or -40.4 dB\n", "The radiation effiency for 10 MHz is 0.22 or -6.5 dB\n" ] } ], "prompt_number": 4 }, { "cell_type": "markdown", "metadata": {}, "source": [ "

Example 7-11.2, Page number: 264

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from math import pi,sqrt\n", "\n", "#Variable declaration\n", "n = 10 #Number of turns (unitless)\n", "dia = 1e-3 #Diameter of copper wire (m)\n", "dia_rod = 1e-2 #Diameter of ferrite rod (m)\n", "len_rod = 10e-2 #Length of ferrite rod (m)\n", "mu_r = 250 - 2.5j #Relative permeability (unitless)\n", "mu_er = 50 #Efeective relative permeability (unitless)\n", "f = 1e6 #Frequency (Hz)\n", "c = 3e8 #Speed of light (m/s)\n", "mu_0 = pi*4e-7 #Absolute permeability (H/m)\n", "\n", "#Calculations\n", "wave_lt = c/f #Wavelength (m)\n", "radius = dia_rod/2\n", "C_l = (2*pi*radius)/(wave_lt) #Circumference of loop (m)\n", "Rr = 197*(mu_er**2)*(n**2)*(C_l**4) #Radiation resistance (ohm)\n", "Rf = 2*pi*f*mu_er*(mu_r.imag/mu_r.real)*mu_0*(n**2)*(pi*radius**2)/len_rod #Loss resistance(ohm)\n", "cond = 1/((7e-5**2)*f*pi*mu_er) #Conductivity (S/m)\n", "delta = 1/(sqrt(f*pi*mu_er*cond)) #Depth of penetration(m)\n", "\n", "RL = n*(C_l/dia)*sqrt((f*mu_0)/(pi*cond)) #Ohmic resistance (ohm)\n", "k = Rr/(RL+abs(Rf)) #Radiation efficiency (unitless)\n", "\n", "L = mu_er*(n**2)*(radius**2)*mu_0/len_rod #Inductance (H)\n", "Q = 2*pi*f*L/(abs(Rf) + Rr + RL) #Ratio of energy stored to energy lost per cycle (unitless)\n", "\n", "fHP = f/Q #Bandwidth at half power (Hz)\n", "\n", "\n", "#Results\n", "print \"The radiation efficiency is \", round(k,11)\n", "print \"The value of Q is \", round(Q,3)\n", "print \"The half-power bandwidth is\", round(fHP), \"Hz\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The radiation efficiency is 6.65e-09\n", "The value of Q is 11.076\n", "The half-power bandwidth is 90289.0 Hz\n" ] } ], "prompt_number": 6 }, { "cell_type": "markdown", "metadata": {}, "source": [ "

Example 7-17.1, Page number: 280

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import numpy as np\n", "\n", "#Variable declaration\n", "Z0 = 376.7 #Intrinsic impdence of free space (ohm)\n", "Zd = 73 + 42.5j #Impedence of infinitesimally thin lambda/2 antenna (ohm)\n", "\n", "#Calculation\n", "Z1 = (Z0**2)/(4*Zd) #Terminal impedence of the lambda/2 slot antenna (ohm)\n", "\n", "#Result\n", "print \"The terminal impedence of the thin lambda/2 slot antenna is\", np.around(Z1), \"ohm\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The terminal impedence of the thin lambda/2 slot antenna is " ] }, { "output_type": "stream", "stream": "stdout", "text": [ "(363-211j) ohm\n" ] } ], "prompt_number": 7 }, { "cell_type": "markdown", "metadata": {}, "source": [ "

Example 7-17.2, Page number: 280

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#Variable declaration\n", "Zd = 67 #Terminal impedence of cylindrical antenna (ohm)\n", "Z0 = 376.7 #Intrinsic impedence of free space (ohm)\n", "L = 0.475 #Length of complementary slot (lambda)\n", "\n", "#Calculation\n", "Z1 = Z0**2/(4*Zd) #Terminal resistance of complementary slot (ohm)\n", "w = 2*L/100 #Width of complementary slot (lambda)\n", "\n", "#Result\n", "print \"The terminal resistance of the complementary slot is\", round(Z1), \"ohm\"\n", "print \"The width of the complementary slot is\", w, \"lambda\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The terminal resistance of the complementary slot is 529.0 ohm\n", "The width of the complementary slot is 0.0095 lambda\n" ] } ], "prompt_number": 8 }, { "cell_type": "markdown", "metadata": {}, "source": [ "

Example 7-17.3, Page number: 281

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#Variable declaration\n", "Zd = 710 #Terminal impdence of cylindrical dipole\n", "Z0 = 376.7 #Intrinsic impedence of free space (ohm)\n", "\n", "#Calculation\n", "Z1 = Z0**2/(4*Zd) #Terminal resistance of complementary slot (ohm)\n", "\n", "#Result\n", "print \"The terminal resistance of the complementary slot is\", round(Z1),\"ohm\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The terminal resistance of the complementary slot is 50.0 ohm\n" ] } ], "prompt_number": 3 }, { "cell_type": "markdown", "metadata": {}, "source": [ "

Example 7-20.1, Page number 288

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "\n", "#Variable declaration\n", "delta_e = 0.2 #path length difference in E-plane (lambda)\n", "delta_h = 0.375 #path length difference in H-plane (lambda)\n", "a_e = 10 #E-plane aperture (lambda)\n", "\n", "\n", "#Calculation\n", "L = a_e**2/(8*delta_e) #Horn length(lambda)\n", "theta_e = 2*math.atan2(a_e,2*L)*180/math.pi #Flare angle in E-plane (degrees)\n", "theta_h = 2*math.acos(L/(L+delta_h))*180/math.pi\n", " #Flare angle in the H-plane (degrees)\n", "a_h = 2*L*math.tan(theta_h/2*math.pi/180) #H-plane aperture (lambda)\n", "\n", "hpbw_e = 56/a_e #Half power beamwidth in E-plane (degrees)\n", "hpbw_h = 67/a_h #Half power beamwidth in H-plane (degrees)\n", "\n", "D = 10*math.log10(7.5*a_e*a_h) #Directivity (dB)\n", "\n", "#Result\n", "print \"The length of the pyramidal horn is\", L,\"lambda\"\n", "print \"The flare angles in E-plane and H-plane are\", round(theta_e,1),\"and\", round(theta_h,2), \"degrees\"\n", "print \"The H-plane aperture is\", round(a_h,1), \"lambda\"\n", "print \"The Half power beamwidths in E-plane and H-plane are\", hpbw_e,\"&\",round(hpbw_h,1),\\\n", "\"degrees\"\n", "print \"The direcivity is\", round(D,1),\"dBi\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The length of the pyramidal horn is 62.5 lambda\n", "The flare angles in E-plane and H-plane are 9.1 and 12.52 degrees\n", "The H-plane aperture is 13.7 lambda\n", "The Half power beamwidths in E-plane and H-plane are 5 & 4.9 degrees\n", "The direcivity is 30.1 dBi\n" ] } ], "prompt_number": 10 } ], "metadata": {} } ] }