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"cells": [
{
"cell_type": "markdown",
"metadata": {},
"source": [
"# Chapter 21: Antenna Measurements

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

### Example 21-2.1, Page number: 720

### "
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from math import pi\n",
"\n",
"#Variable declaration\n",
"f = 900e6 #Frequency (Hz)\n",
"length = 25e-3 #Length of antenna (m)\n",
"len_cell = 110e-3 #Length of handset chassis (m)\n",
"c = 3e8 #Speed of light (m/s)\n",
"del_L = 0.5 #Peak to Peak measurement uncertainty (dB)\n",
"\n",
"#Calculations\n",
"Dm = length + len_cell #Maximum Dimension of antenna (m)\n",
"wave_lt = c/f #Wavelength (m)\n",
"r_rnf = (wave_lt/(2*pi)) #Outer boundary of reactive near field (m)\n",
"\n",
"r_ff = 2*(Dm**2)/wave_lt #Fraunhofer region (m)\n",
"\n",
"r2_ff = r_rnf/(10**(del_L/40)-1) \n",
" #Minimum distance where effect of near field is small (m)\n",
"\n",
"r3_ff = 2*Dm/(10**(del_L/10)-1)\n",
" #Minimum distance where effect of rotation of AUT is small (m)\n",
"\n",
"#Result\n",
"print \"The Outer boundary of reactive near field is at a distance\", round(r_rnf,3),\"m\"\n",
"print \"The Fraunhofer region starts at a distance\", round(r_ff,3),\"m\"\n",
"print \"The Minimum distance where effect of near field is small enough is\",\\\n",
" round(r2_ff,1),\"m\"\n",
"print \"The Minimum distance where effect of rotation of AUT is small enough \\\n",
"is\", round(r3_ff,1),\"m\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The Outer boundary of reactive near field is at a distance 0.053 m\n",
"The Fraunhofer region starts at a distance 0.109 m\n",
"The Minimum distance where effect of near field is small enough is 1.8 m\n",
"The Minimum distance where effect of rotation of AUT is small enough is 2.2 m\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"

### Example 21-2.2, Page number: 720

### "
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from math import pi\n",
"\n",
"#Variable declaration\n",
"horn_len = 350e-3 #Length of horn (m)\n",
"ap_wid = 200e-3 #Aperture width (m)\n",
"ap_hei = 150e-3 #Aperture height (m)\n",
"del_L = 0.2 #Peak to peak uncertainty (dB)\n",
"f = 10e9 #Frequency (Hz)\n",
"c = 3e8 #Speed of light (m/s)\n",
"\n",
"#Calculations\n",
"wave_lt = c/f #Wavelength (m)\n",
"r_rnf = wave_lt/(2*pi) ##Outer boundary of reactive near field (m)\n",
"\n",
"r_ff = 2*(ap_wid**2)/wave_lt #Fraunhofer region (m)\n",
"\n",
"r2_ff = r_rnf/(10**(del_L/40)-1) \n",
" #Minimum distance where effect of near field is small (m)\n",
"\n",
"r3_ff = 2*horn_len/(10**(del_L/10)-1)\n",
" #Minimum distance where effect of rotation of AUT is small (m)\n",
"\n",
"#Result\n",
"print \"The Outer boundary of reactive near field is at a distance\", round(r_rnf,4),\"m\"\n",
"print \"The Fraunhofer region starts at a distance\", round(r_ff,1),\"m\"\n",
"print \"The Minimum distance where effect of near field is small enough is\",\\\n",
" round(r2_ff,2),\"m\"\n",
"print \"The Minimum distance where effect of rotation of AUT is small enough \\\n",
"is\", round(r3_ff,1),\"m\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The Outer boundary of reactive near field is at a distance 0.0048 m\n",
"The Fraunhofer region starts at a distance 2.7 m\n",
"The Minimum distance where effect of near field is small enough is 0.41 m\n",
"The Minimum distance where effect of rotation of AUT is small enough is 14.9 m\n"
]
}
],
"prompt_number": 3
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"

### Example 21-2.3, Page number: 721

### "
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Variable declaration\n",
"D = 0.5 #Antenna diameter (m)\n",
"f = 300e9 #Frequency (Hz)\n",
"c = 3e8 #Speed of light (m/s)\n",
"\n",
"#Calculations\n",
"wave_lt = c/f #Wavelength (m)\n",
"r_ff = 2*(D**2)/wave_lt #Fraunhofer region (m)\n",
"\n",
"#Result\n",
"print \"The Fraunhofer region starts at a distance\", r_ff,\"m\"\n",
"print \"At 300 GHz the attenuation of the atmosphere is around 10dB/km making\\\n",
" the measurement difficult in full-size ranges\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The Fraunhofer region starts at a distance 500.0 m\n",
"At 300 GHz the attenuation of the atmosphere is around 10dB/km making the measurement difficult in full-size ranges\n"
]
}
],
"prompt_number": 6
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"

### Example 21-4.1, Page number: 726

### "
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from math import pi\n",
"\n",
"#Variable declaration\n",
"D = 1 #Diameter of antenna (m)\n",
"f = 10e9 #Frequency (Hz)\n",
"c = 3e8 #Speed of light (m/s)\n",
"\n",
"#Calculations\n",
"wave_lt = c/f #Wavelength (m)\n",
"hpbw = 70*wave_lt/D #Half power beamwidth (degrees)\n",
"mea_dist = 2*(D**2)/wave_lt #Measurement distance (m)\n",
"trav_dist = hpbw*pi*mea_dist/180 #Traverse distance (m)\n",
"taper = ((0.5/(trav_dist/2))**2)*(-3) #Amplitude taper (dB)\n",
"\n",
"#Result\n",
"print \"The amplitude taper is\", round(taper,1), \"dB\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The amplitude taper is -0.5 dB\n"
]
}
],
"prompt_number": 7
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"

### Example 21-4.2, Page number: 735

### "
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from math import log10\n",
"\n",
"#Variable declaration\n",
"pat_lev1 = -22.3 #Pattern level maximum (dB)\n",
"pat_lev2 = -23.7 #Pattern level minimum (dB)\n",
"\n",
"#Calculations\n",
"S = abs(pat_lev2-pat_lev1) #Amplitude ripple (dB)\n",
"a = (pat_lev1+pat_lev2)/2 #Pattern level (dB)\n",
"\n",
"R = a + 20*log10((10**(S/20) - 1)/(10**(S/20) + 1))\n",
" #Reflectivity (dB)\n",
"\n",
"#Result\n",
"print \"The reflectivity is\", round(R),\"dB\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The reflectivity is -45.0 dB\n"
]
}
],
"prompt_number": 8
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"

### Example 21-5.1, Page number: 739

### "
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from math import pi, sin, cos, log10\n",
"\n",
"#Variable declaration\n",
"En = 1 #Field illuminating the AUT (unitless)\n",
"tilt_diff = 88 #Difference in tilt angles (degrees)\n",
"\n",
"#Calculations\n",
"En_pol = En*sin(tilt_diff*pi/180) #Co-polar component of field (unitless)\n",
"En_crosspol = En*cos(tilt_diff*pi/180)\n",
" #Cross-polar component of field (unitless)\n",
"meas_cross = 20*log10(En_crosspol)\n",
"\n",
"#Result\n",
"print \"The measure cross-polar level is\", round(meas_cross), \"dB\\\n",
" relative to the co-polar field\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The measure cross-polar level is -29.0 dB relative to the co-polar field\n"
]
}
],
"prompt_number": 9
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"

### Example 21-5.2, Page number: 743

### "
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from math import pi, log10\n",
"\n",
"#Variable declaration\n",
"f = 1.4e9 #Frequency (Hz)\n",
"Tant = 687 #Increase in antenna temperature (K)\n",
"phy_ap = 2210 #Physical aperture (m^2)\n",
"S = 1590 #Flux density of Cygnus A (Jy)\n",
"k = 1.38e-23 #Boltzmann's constant (J/k)\n",
"c = 3e8 #Speed of light (m/s)\n",
"\n",
"#Calculations\n",
"wave_lt = c/f #Wavelength (m)\n",
"gain = (8*pi*k*Tant)/(S*(10**-26)*wave_lt**2) #Gain(unitless)\n",
"gain_db = 10*log10(gain) #Gain (dBi)\n",
"\n",
"Ae = gain*wave_lt**2/(4*pi) #Effective area (m^2)\n",
"\n",
"eff_ap = Ae/phy_ap #Aperture efficiency (unitless)\n",
"\n",
"#Result\n",
"print \"The gain of the antenna is\", round(gain_db), \"dBi\"\n",
"print \"The aperture efficiency is\", round(eff_ap,2),\"or\",round(eff_ap*100),\"percent\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The gain of the antenna is 55.0 dBi\n",
"The aperture efficiency is 0.54 or 54.0 percent\n"
]
}
],
"prompt_number": 10
}
],
"metadata": {}
}
]
}