Introduction in Telecommunication 121009

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Introduction in Telecommunication(121009) Chris
Roeloffzen
Chair Telecommunication engineering (EWI) Floor
8 HOGEKAMP EL/TN building (north) Telephone 489
2804 E-mail c.g.h.roeloffzen_at_el.utwente.nl
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Today Lecture 10
Chapter 10 Electromagnetic Wave Propagation
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Contents of the course
Lecture 1 - 3 Introduction Chapter 1
Introduction to Electronic Communications Chapter
2 Signal Analysis and Mixing Lecture 4 - 7
CW modulation Chapter 4 Amplitude modulation,
Transmission Chapter 5 Amplitude modulation,
Reception Chapter 6 Single-side banded
Communication Systems Chapter 7 Angle
Modulation Transmission Chapter 8 Angle
Modulation Receivers Lecture 10 - 13
Media Chapter 12 Metallic Transmission Lines
Chapter 13 Optical Fiber Transmission
media Chapter 14 Electromagnetic Wave
Propagation Chapter 15 Antennas Lecture 14 -
15 Digital Communication Chapter 9 Digital
Modulation Chapter 10 Digital
Transmission Lecture 16 ????????????????? For
specific information see www.el.utwente.nl/te/edu
cation/education.htm
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Chapter 14 Electromagnetic Wave Propagation

• EM Wave
• Plane and Spherical waves
• Isotropic source
• EM wave attenuation
• Refraction and Reflection
• Huygens principle
• Interference
• Propagation of EM Waves sky, ground, space,
  duct
• Free space path loss

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Electromagnetic Spectrum
? wavelength (meters) c velocity of light
(300.000.000 meters per second) f frequency
(hertz)
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Rays and Wavefronts Plane wave
http//www.phy.ntnu.edu.tw/java/emWave/emWave.html
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Rays and Wavefronts Spherical wave
http//physics.nad.ru/Physics/English/1wa_tmp.htm
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Rays and Wavefronts Isotropic source
P power density Prad total power radiated
W R radius of the sphere
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EM Wave Attenuation and Absorption
Attenuation is due to spherical spreading of the
wave, non of the radiated power is lost
Absorption is due to energy transfer from the
EM-wave to the atoms and molecules of the
atmosphere
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Properties of Radio Waves Refraction
N number of electrons per cm2 f frequency
(kHz)
n1 refractive index material 1 n2 refractive
index material 2 ?1 angle of incidence ?2
angle of refraction
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Refraction in a gradient medium
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Properties of Radio Waves Reflection
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Reflection from a semirough surface
Rayleighs criterion for smooth surfaces
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Diffraction Huygens principle for a plane wave
http//id.mind.net/zona/mstm/physics/waves/propag
ation/huygens3.html
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Diffraction Huygens principle
slot
edge
http//physics.nad.ru/Physics/English/1wd_tmp.htm
http//www.rit.edu/visualiz/projects/diffraction.
html
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Interference
http//physics.nad.ru/Physics/English/2wa_tmp.htm
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Terrestrial propagation of EM Waves
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Surface wave propagation
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Space wave propagation
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Radio Horizon
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Duct propagation
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Sky wave propagation
Ionosphere
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Sky wave
Higher RF frequencies are less refracted
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Virtual height
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Sky wave Skip Distance
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Sky wave daytime vs. nighttime propagation
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Free-space path loss (spreading loss)
Lp free-space path loss D distance
(kilometers) f frequency (hertz) ? wavelength
(meters) c velocity of light in free space