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},
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"worksheets": [
{
"cells": [
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<h1>Chapter 24: Space Wave Propagation<h1>"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<h3>Example 24-9.1, Page number: 808<h3>"
]
},
{
"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": [
"<h3>Example 24-9.2, Page number: 809<h3>"
]
},
{
"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": [
"<h3>Example 24-9.3, Page number: 809<h3>"
]
},
{
"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": [
"<h3>Example 24-9.4, Page number: 809<h3>"
]
},
{
"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": [
"<h3>Example 24-9.5, Page number: 809<h3>"
]
},
{
"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": [
"<h3>Example 24-12.1, Page number: 812<h3>"
]
},
{
"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": [
"<h3>Example 24-14.1, Page number: 813<h3>"
]
},
{
"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": {}
}
]
}