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Input Impedance of a Vertical Electric Dipole above earth

Input Impedance of a Vertical Electric Dipole above earth. Thomas Ng, RHIT Advisor: Prof. Xiao-Bang Xu SURE Program 2004 Clemson University July 27, 2004. Outline. Why is this hard ? Why is this interesting ? How do we do it ?. R. Dipole. h. Air. Lossy Earth. Historical Overview.

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Input Impedance of a Vertical Electric Dipole above earth

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  1. Input Impedance of a Vertical Electric Dipole above earth Thomas Ng, RHIT Advisor: Prof. Xiao-Bang Xu SURE Program 2004 Clemson University July 27, 2004

  2. Outline • Why is this hard ? • Why is this interesting ? • How do we do it ?

  3. R Dipole h Air Lossy Earth Historical Overview • Marconi’s Wireless Telegraph 1901 • Sommerfeld’s Formulation 1909 • Sommerfeld-Type Integrals Observation

  4. Sommerfeld Integrals • No analytic solution • Oscillate Rapidly • Decay Slowly • Infinite

  5. Applications • Design and development of communications systems • Efficiency and cost considerations • Scattering Problems • Mine Detection

  6. z2 2*l z1 z0 h Impedance Problem • Induced EMF Method • Sinusoidal Current Approximation Half-Wavelength Dipole Air Lossy Earth, εr

  7. Impedance Problem

  8. Complex Image Technique

  9. Complex Image Technique

  10. CIT Results

  11. CIT Results

  12. CIT Results

  13. Exact Image Theory • Laplace Transforms performed on reflection coefficients • Change order of integration

  14. Exact Image Theory • Eliminates bad behavior of Sommerfeld Integral

  15. Superposition Induced EMF Method Impedance Problem

  16. Comparing Results: Zin

  17. Comparing Results: Time

  18. Conclusions • Varying ground conditions affect input impedance • There are different ways to avoid Sommerfeld-type Integrals • Accuracy and Computation Time tradeoff

  19. Future Work • More accurate expression for antenna current • Investigate EIT method more completely

  20. Acknowledgements • Prof. Xiao Bang Xu • Prof. Daniel L. Noneaker

  21. Questions ?

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