Electromagnetic Wave

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In wireless communication, we frequently use an electromagnetic wave. In this presentation, we can study wave equation, reflection, plane wave, and transmission line.

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Electromagnetic Wave

  1. 1. Antenna Engineering CHO, Yong Heui Electromagnetic Wave
  2. 2. 1. Wave equation E and H wave equation  <ul><li>: E wave equation </li></ul><ul><li>: H wave equation </li></ul>Proof: Faraday’s law + curl operator Sourceless system
  3. 3. Wave propagation  <ul><li>Propagation direction: z-direction </li></ul><ul><li>: simplified wave equation </li></ul>Cartesian coordinate system 1. Wave equation
  4. 4. Wave propagation  <ul><li>Assumption: </li></ul><ul><li>Propagation: constant wavefront </li></ul>1. Wave equation
  5. 5. Wave velocity  <ul><li>Substitution: </li></ul><ul><li>Wave velocity: </li></ul><ul><li>Uniqueness theorem </li></ul>1. Wave equation
  6. 6. Why’s EM wave propagate?  <ul><li>Movement, variance </li></ul><ul><li>Importance of two curl equations </li></ul>1. Wave equation
  7. 7. Complex number: time  <ul><li>Circuit theory </li></ul><ul><li>EM theory </li></ul>1. Wave equation
  8. 8. 2. Plane wave EM power  <ul><li>Poynting vector </li></ul><ul><li>EM power </li></ul><ul><li>Example of plane wave: </li></ul>Approximation ( 근사 )
  9. 9. Wave impedance  <ul><li>Ratio of E and H </li></ul><ul><li>Resistance </li></ul>2. Plane wave
  10. 10. Reflection and transmission  <ul><li>Incident wave </li></ul><ul><li>Reflected wave </li></ul><ul><li>Transmitted wave </li></ul>2. Plane wave
  11. 11. Boundary conditions  <ul><li>E continuity at z = 0 </li></ul><ul><li>H continuity at z = 0 </li></ul><ul><li>Reflection and transmission coefficient </li></ul>2. Plane wave
  12. 12. Transparency ( 투명 )  <ul><li>No reflection: transparency </li></ul><ul><li>Total reflection </li></ul><ul><ul><li>: PEC (Electric Conductor) </li></ul></ul><ul><ul><li>: PMC (Magnetic Conductor) </li></ul></ul>2. Plane wave
  13. 13. Lossy media  <ul><li>Ohm’s law: induced current density </li></ul><ul><li>Complex permittivity </li></ul>Stealth 2. Plane wave
  14. 14. Skin depth  <ul><li>Conductor </li></ul><ul><li>Skin depth: </li></ul><ul><ul><li>Wavenumber: </li></ul></ul>Water 2. Plane wave
  15. 15. Polarization: direction of E field 2. Plane wave  <ul><li>LP: Linear Polarization, co and cross </li></ul><ul><li>CP: Circular Polarization, AR (Axial Ratio) </li></ul><ul><li>EP: Elliptic Polarization </li></ul>Vertical LP Horizontal LP
  16. 16. Wave propagation  3. Tx Line Theory
  17. 17. Distributed element  <ul><li>Lumped element: R, L, C </li></ul> <ul><li>Distributed element: tx line </li></ul>3. Tx Line Theory
  18. 18. Transmission line equation   Tx line Tx line modeling 3. Tx Line Theory
  19. 19. Wave solution  <ul><li>Traveling wave solution </li></ul><ul><ul><li>Voltage: </li></ul></ul><ul><ul><li>Current: </li></ul></ul>3. Tx Line Theory
  20. 20. Characteristic impedance  <ul><li>Important parameter in tx line: </li></ul>3. Tx Line Theory
  21. 21. Reflection coefficient   <ul><li>Voltage wave continuity conditions </li></ul><ul><li>Current wave continuity conditions </li></ul>3. Tx Line Theory
  22. 22. Comparison with circuit theory 3. Tx Line Theory
  23. 23. Comparison with circuit theory 3. Tx Line Theory
  24. 24. Comparison with circuit theory 3. Tx Line Theory
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