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

Chapter 24: Space Wave Propagation

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

Example 24-9.1, Page number: 808

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from math import sqrt\n", "\n", "#Variable declaration\n", "tx_h = 49.0 #Transmitting antenna height (m)\n", "rx_h = 25.0 #Receiving antenna height (m)\n", "f = 100e6 #Frequency (Hz)\n", "tx_p = 100.0 #Transmitted power (W)\n", "c = 3e8 #Speed of light (m/s)\n", "a = 6370 #Earth's radius (km)\n", "\n", "#Calculations\n", "wave_lt = c/f #Wavelength (m)\n", "d0 = sqrt(2*(4.0/3.0)*(a/1000.0))*(sqrt(tx_h)+sqrt(rx_h))\n", " #Line of Sight (LOS) distance (km)\n", "d = d0*1000 #LOS (m)\n", "Er = (88*sqrt(tx_p)/(wave_lt*(d**2)))*tx_h*rx_h\n", " #Received signal strength (W)\n", "\n", "#Result\n", "print \"The Line of Sight distance is\", round(d0,2), \"km\"\n", "print \"The received signal strength is\", round(Er,6), \"W\"\n", "\n", "#The mistake is in the calculation of (88*sqrt(tx_p)/(wave_lt*(d**2))) where four orders of\n", "#magnitude are ignored in the resulting calculation." ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The Line of Sight distance is 49.46 km\n", "The received signal strength is 0.000147 W\n" ] }, { "metadata": {}, "output_type": "pyout", "prompt_number": 1, "text": [ "'The mistake is in the calculation of (88*sqrt(tx_p)/(wave_lt*(d**2))) where four orders of\\nmagnitude are ignored in the resulting calculation.'" ] } ], "prompt_number": 1 }, { "cell_type": "markdown", "metadata": {}, "source": [ "

Example 24-9.2, Page number: 809

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from math import sqrt\n", "\n", "#Variable declaration\n", "tx_h = 144 #Transmitting antenna height (m)\n", "rx_h = 25 #Receiving antenna height (m)\n", "k = 4.0/3.0 #Equivalent earth radius/Actual earth radius (unitless)\n", "a = 6370 #Radius of earth (km)\n", "\n", "#Calculations\n", "los = 4.12*(sqrt(tx_h) + sqrt(rx_h)) #Line of sight distance (km)\n", "\n", "horz = sqrt(2*k*a*(tx_h/1000.0)) #Surface range to radio horizon from radar (km)\n", "\n", "#Result\n", "print \"The Radio horizon distance from radar is\", round(horz,2),\"km\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The Radio horizon distance from radar is 49.46 km\n" ] } ], "prompt_number": 4 }, { "cell_type": "markdown", "metadata": {}, "source": [ "

Example 24-9.3, Page number: 809

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from math import sqrt\n", "\n", "#Variable declaration\n", "tx_h = 100 #Transmitting antenna height (m)\n", "rx_h = 16 #Receiving antenna height (m)\n", "tx_p = 40e3 #Transmitting antenna power radiation (W)\n", "f = 100e6 #Frequency (Hz)\n", "d = 10e3 #Distance (m)\n", "c = 3e8 #Speed of light (m/s)\n", "E = 1e-3 #Signal strength (V/m)\n", "\n", "#Calculations\n", "los = 4.12*(sqrt(tx_h) + sqrt(rx_h)) #LOS distance (km)\n", "wave_lt = c/f #Wavelength (m)\n", "\n", "Es = (88*sqrt(tx_p)/(wave_lt*(d**2)))*tx_h*rx_h\n", " #Field strength at distance d (V/m)\n", "\n", "dsig = sqrt(88*sqrt(tx_p)*tx_h*rx_h/(wave_lt*E))\n", " #Distance at which field strength reduces to 1mV/m\n", "\n", "#Result\n", "print \"The LOS distance is\", los, \"km\"\n", "print \"The field strength at 10km is\", round(Es,5),\"V/m\"\n", "print \"The distance at which field strength is 1mV/m is\", round(dsig,-1), \"m\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The LOS distance is 57.68 km\n", "The field strength at 10km is 0.09387 V/m\n", "The distance at which field strength is 1mV/m is 96880.0 m\n" ] } ], "prompt_number": 8 }, { "cell_type": "markdown", "metadata": {}, "source": [ "

Example 24-9.4, Page number: 809

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from math import pi\n", "\n", "#Variable declaration\n", "gain = 10 #Antenna gain (dB)\n", "Wt = 500 #Power radiation (W)\n", "d = 15e3 #Distance (m)\n", "Wr = 2e-6 #Received power (W)\n", "\n", "#Calculations\n", "Ae = Wr*(4*pi*(d**2))/(Wt*gain) #Effective area (m^2)\n", "\n", "#Result\n", "print \"The effective area of the receiving antenna is\", round(Ae,2), \"m^2\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The effective area of the receiving antenna is 1.13 m^2\n" ] } ], "prompt_number": 9 }, { "cell_type": "markdown", "metadata": {}, "source": [ "

Example 24-9.5, Page number: 809

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from math import sqrt\n", "\n", "#Variable declaration\n", "h = 1000 #Height of duct (m)\n", "delM = 0.036 #Change in refractive modulus (unitless)\n", "c = 3e8 #Speed of light (m/s)\n", "\n", "#Calculations\n", "wl_max = 2.5*h*sqrt(delM*1e-6) #Maximum wavelength (m)\n", "fmax = c/wl_max #Maximum frequency (Hz)\n", "\n", "#Result\n", "print \"The maximum frequency that can be transmitted is\", round(fmax/1e6,1),\"MHz\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The maximum frequency that can be transmitted is 632.5 MHz\n" ] } ], "prompt_number": 10 }, { "cell_type": "markdown", "metadata": {}, "source": [ "

Example 24-12.1, Page number: 812

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from math import pi,sqrt\n", "\n", "#Variable declaration\n", "gain = 10 #Gain of transmitting antenna (dB)\n", "P = 100 #Radiating power (W)\n", "f = 1e6 #Frequency (Hz)\n", "rx_gain = 15 #Gain of receiving antenna (dB)\n", "d = 20e3 #Distance (m)\n", "c = 3e8 #Speed of light (m/s)\n", "v = 1000 #scattering volume (m^3)\n", "sigma = 0.1 #Effective scattering cross-section (m^2)\n", "\n", "#Calculations\n", "wl = c/f #Wavelength (m)\n", "Pr_a = P*gain*rx_gain*(wl**2)/(4*pi*(4*pi*(d**2)))\n", " #Received power in case (a) (W)\n", "F = (2*sqrt(sigma*v))/(d*sqrt(pi)) #Attenuation Factor (unitless)\n", "Pr_b = Pr_a*F #Received power in case (b) (W)\n", "\n", "\n", "#Result\n", "print \"The received power in case (a) is\", round(Pr_a,5), \"W\"\n", "print \"The received power in case (b) is\", round(Pr_b,10), \"W\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The received power in case (a) is 0.02137 W\n", "The received power in case (b) is 1.20581e-05 W\n" ] } ], "prompt_number": 18 }, { "cell_type": "markdown", "metadata": {}, "source": [ "

Example 24-14.1, Page number: 813

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from math import log10\n", "\n", "#Variable declaration\n", "d = 3000 #Distance (km)\n", "f = 3e3 #Frequency (MHz)\n", "\n", "#Calculations\n", "path_l = 32.45 + 20*log10(f) + 20*log10(d)\n", "\n", "#Result\n", "print \"The path loss between the two points is\", round(path_l,3), \"dB\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The path loss between the two points is 171.535 dB\n" ] } ], "prompt_number": 19 } ], "metadata": {} } ] }