EM Wave Propagation
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The document provides an overview of electromagnetic (EM) waves, including their properties, such as their speed, energy distribution, and behavior when interacting with different media. It discusses the electromagnetic spectrum, various types of waves within it, and the concept of wave propagation in lossy dielectrics, detailing important coefficients that describe attenuation and phase. Additionally, it covers the characteristics of plane waves in free space, emphasizing fundamental parameters relevant to EM wave propagation.
EM Wave Propagation
- 1. Electromagnetic Wave Propagation IRFAN SULTAN INSTRUCTOR (TELECOM.) GOVT. COLLEGE OF TECHNOLOGY
- 2. Contents Introduction to EM Waves. Electromagnetic Spectrum Wave Propagation in Lossy Dielectrics Plane Waves in Free Space Plane Waves in Good Conductors
- 3. Introduction to EM-Waves Electromagnetic Waves, also abbreviated as EM-Waves, are the waves which consist of both Electric and Magnetic Fields and travel at a speed same as that of light, i.e. 3x108 m/sec All forms of electromagnetic radiation consist of perpendicular oscillating electric and magnetic fields.
- 4. Properties of EM-Waves Invisible Travel at speed of light Consist of Electric and Magnetic fields Electric Field, Magnetic Field and Direction of Propagation of an EM wave are all perpendicular to each other Their Electric and Magnetic fields cannot be separated from each other The total energy of an EM wave is equally divided between Electric and Magnetic fields When they pass through a metallic conductor they produce voltage across the conductor
- 5. Properties of EM-Waves They don’t need any medium to travel Their intensity is same all around in free space When they travel from one place to another their power (intensity) is reduced, i.e. they suffer from attenuation When they enter from one medium to another: Their form of energy changes, i.e. they suffer from Absorption They are diverted from their path, this process is called refraction When they pass through a hole they bent along sides when leaving the hole, this process is called Deflection
- 6. Refraction, Absorption and Diffraction Refraction Reflection Diffraction Absorption
- 7. Electromagnetic Spectrum EM Spectrum is the range of wavelengths or frequencies over which electromagnetic radiation extends. It consists of different frequency bands which are basically groups of certain frequency ranges.
- 9. Waves Longitudinal Waves Transverse Waves Electromagnetic Waves Electromagnetic Spectrum Radiowave Microwave Infra-Red Light Ultra-Violet X-ray Gamma ray Applications Sound waves Classified into Comprises of
- 10. Some tips to help you to remember: EM Spectrum Raja’s Mother Is Visiting Uncle Xavier’s Garden Visible Light Spectrum Run Off You Girls Boys In View Radio wave Micro wave Infra-red Rays Visible light Ultra-violet ray X-rays Gamma rays red orange yellow green blue indigo violet
- 11. Wave Propagation in Lossy Dielectrics A Lossy Dielectric is basically a medium which reduce the power of EM waves, due to its “Poor Condition”, when they travel through it. In other words, a Lossy Dielectric is a practical conducting medium that is neither a good conductor nor a good insulator. The following terms are used to describe the losses in a propagating wave: Attenuation Coefficient 𝛼 Phase Coefficient 𝛽
- 12. Attenuation Coefficient is measured in Neper Per Meter (Np/m) or Decibel Per Meter (dB/m) 1Np = 20log(e) = 8.686 dB Formulas for Velocity and Wavelength of a wave are: Wave Propagation in Lossy Dielectrics Formulas for Attenuation and Phase coefficients are: 𝜎 = sigma = Conductivity 𝜇 = mu = Permeability 𝜔 = omega = Angular velocity ε = epsilon = Permittivity
- 13. Plane Waves in Free Space This is a special case for which: Permeability 𝜇 = 𝜇𝑜 (Permeability of free space) = µ0 = 4π × 10−7 H Conductivity 𝜎 = 0 Permittivity ε = εo (Permittivity of free space) = 8.85 x 10-12 F/m
Editor's Notes
- #14: The permeability constant (µ0), also known as the magnetic constant or the permeability of free space, is a measure of the amount of resistance encountered when forming a magnetic field in a classical vacuum. The magnetic constant has the exact (defined) value (µ0 = 4π × 10−7 H. Permittivity: the ability of a substance to store electrical energy in an electric field.
- #15: Skin depth is a measure of how far electrical conduction takes place in a conductor, and is a function of frequency. At DC (0 Hz) the entire conductor is used, no matter how thick it is. The skin depth is a measure of the penetration of a plane electromagnetic wave into a material.