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{
"metadata": {
"name": ""
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<h1>Chapter 23: Ground Wave Propagation<h1>"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<h3>Example 23-1.1, Page number: 783<h3>"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Variable declaration\n",
"f1 = 0.1 #Frequency (MHz)\n",
"f2 = 1.0 #Frequency (MHz)\n",
"f3 = 10.0 #Frequency (MHz)\n",
"\n",
"#Calculations\n",
"d1 = 50/(f1**(1.0/3)) #Distance for f1 (miles)\n",
"d2 = 50/(f2**(1.0/3)) #Distance for f2 (miles)\n",
"d3 = 50/(f3**(1.0/3)) #Distance for f3 (miles)\n",
"\n",
"#Result\n",
"print \"The distance for 100kHz is\", round(d1,2), \"miles\"\n",
"print \"The distance for 1MHz is\", d2, \"miles\"\n",
"print \"The distance for 10MHz is\", round(d3,2), \"miles\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The distance for 100kHz is 107.72 miles\n",
"The distance for 1MHz is 50.0 miles\n",
"The distance for 10MHz is 23.21 miles\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<h3>Example 23-2.1, Page number: 786<h3>"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from math import pi,sin\n",
"\n",
"#Variable declaration\n",
"f = 3e6 #Frequency (Hz)\n",
"sigma = 0.5 #Standard deviation of surface irregularities (unitless)\n",
"theta = 30 #Angle of incidence as measured from normal angle (degrees)\n",
"c = 3e8 #Speed of light (m/s)\n",
"\n",
"#Calculations\n",
"wave_lt = c/f #Wavelength (m)\n",
"R = 4*pi*sigma*sin(theta*pi/180)/wave_lt\n",
" #Roughness factor (unitless)\n",
"\n",
"#Result\n",
"print \"The roughness factor is\", round(R,9)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The roughness factor is 0.031415927\n"
]
}
],
"prompt_number": 2
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<h3>Example 23-2.2, Page number: 786<h3>"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from math import pi,sin\n",
"\n",
"#Variable declaration\n",
"f = 10e6 #Frequency (Hz)\n",
"sigma = 5 #Standard deviation of surface irregularities (unitless)\n",
"theta1 = 30 #Angle of incidence as measured from normal angle (degrees)\n",
"theta2 = 45 #Angle of incidence as measured from normal angle (degrees)\n",
"theta3 = 60 #Angle of incidence as measured from normal angle (degrees)\n",
"c = 3e8 #Speed of light (m/s)\n",
"\n",
"#Calculations\n",
"wave_lt = c/f #Wavelength (m)\n",
"R1 = 4*pi*sigma*sin(theta1*pi/180)/wave_lt \n",
" #Roughness factor for theta1 (unitless)\n",
"R2 = 4*pi*sigma*sin(theta2*pi/180)/wave_lt\n",
" #Roughness factor for theta2 (unitless)\n",
"R3 = 4*pi*sigma*sin(theta3*pi/180)/wave_lt\n",
" #Roughness factor for theta3 (unitless)\n",
"\n",
"#Result\n",
"print \"The roughness factor for 30 degrees is\", round(R1,4)\n",
"print \"The roughness factor for 45 degrees is\", round(R2,3)\n",
"print \"The roughness factor for 60 degrees is\", round(R3,4)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The roughness factor for 30 degrees is 1.0472\n",
"The roughness factor for 45 degrees is 1.481\n",
"The roughness factor for 60 degrees is 1.8138\n"
]
}
],
"prompt_number": 4
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<h3>Example 23-2.3, Page number: 787<h3>"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Variable declaration\n",
"f1 = 0.3 #Frequency (MHz)\n",
"f2 = 1 #Frequency (MHz)\n",
"f3 = 3 #Frequency (MHz)\n",
"sigma = 4e-5 #Standard deviation of surface irregularities (unitless)\n",
"\n",
"#Calculations\n",
"x1 = (18e3)*sigma/f1 #Parameter x for f1 (unitless)\n",
"x2 = (18e3)*sigma/f2 #Parameter x for f2 (unitless)\n",
"x3 = (18e3)*sigma/f3 #Parameter x for f3 (unitless)\n",
"\n",
"#Result\n",
"print \"The parameter x for 0.3MHz is\", x1\n",
"print \"The parameter x for 1MHz is\", x2\n",
"print \"The parameter x for 3MHz is\", x3"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The parameter x for 0.3MHz is 2.4\n",
"The parameter x for 1MHz is 0.72\n",
"The parameter x for 3MHz is 0.24\n"
]
}
],
"prompt_number": 13
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<h3>Example 23-5.1, Page number: 790<h3>"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from math import pi, sqrt\n",
"\n",
"#Variable declaration\n",
"f1 = 5e3 #Frequency (Hz)\n",
"f2 = 50e3 #Frequency (Hz)\n",
"f3 = 500e3 #Frequency (Hz)\n",
"sigma = 5e-5 #Standard deviation of surface irregularities (unitless)\n",
"eps_r = 15.0 #Relative permittivity (unitless)\n",
"mu = pi*4e-7 #Absolute Permeability (H/m)\n",
"\n",
"#Calculations\n",
"w1 = 2*pi*f1 #Angular frequency (rad/s)\n",
"w2 = 2*pi*f2 #Angular frequency (rad/s)\n",
"w3 = 2*pi*f3 #Angular frequency (rad/s)\n",
"\n",
"\n",
"Zs1 = sqrt((w1*mu)/sqrt(sigma**2 + (w1**2)*eps_r))\n",
" #Surface impedence for f1 (ohm)\n",
"Zs2 = sqrt((w2*mu)/sqrt(sigma**2 + (w2**2)*eps_r))\n",
" #Surface impedence for f2 (ohm)\n",
"Zs3 = sqrt((w3*mu)/sqrt(sigma**2 + (w3**2)*eps_r))\n",
" #Surface impedence for f3 (ohm)\n",
"\n",
"#Result\n",
"print \"The surface impedence for 5kHz is\", round(Zs1,5), \"ohms\"\n",
"print \"The surface impedence for 50kHz is\", round(Zs2,5), \"ohms\"\n",
"print \"The surface impedence for 500kHz is\", round(Zs3,5), \"ohms\"\n",
"\n",
"#There has been a numerical mistake in the calculation/substitution of square root of\n",
"#(sigma**2 + (w1**2)*eps_r) and in the second case, the mistake in the calculation of\n",
"#(w2*mu)/sqrt(sigma**2 + (w2**2)*eps_r)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The surface impedence for 5kHz is 0.00057 ohms\n",
"The surface impedence for 50kHz is 0.00057 ohms\n",
"The surface impedence for 500kHz is 0.00057 ohms\n"
]
}
],
"prompt_number": 24
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<h3>Example 23-7.1, Page number: 793<h3>"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from math import pi, atan, cos\n",
"\n",
"#Variable declaration\n",
"f = 2.0 #Frequency (MHz)\n",
"sigma = 5e-5 #Standard deviation of surface irregularities (unitless)\n",
"eps_r = 15.0 #Relative permittivity (unitless)\n",
"d = 20e3 #Distance (m)\n",
"eff = 0.5 #Antenna efficiency (unitless)\n",
"c = 3e8 #Speed of light (m/s)\n",
"E1 = 0.5e-3 #Ground wave electric field strength (V/m)\n",
"\n",
"#Calculations\n",
"wave_lt = c/(f*10**6) #Wavelength (m)\n",
"x = (18e3)*sigma/f #Parameter x (unitless)\n",
"\n",
"b = atan((eps_r + 1)/x) #Phase constant (unitless)\n",
"\n",
"p = (pi/x)*(d/wave_lt)*cos(b) #Numerical distance (unitless)\n",
"\n",
"A = (2 + 0.3*p)/(2 + p + 0.6*(p**2)) #Reduction factor (unitless)\n",
"\n",
"E_t = E1 * d/A\n",
"\n",
"#Result\n",
"print \"The Electric field strength at the transmitted end is\", round(E_t,2),\"V/m\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The Electric field strength at the transmitted end is 445.72 V/m\n"
]
}
],
"prompt_number": 25
}
],
"metadata": {}
}
]
}
|
