EEE 212 Figures are from Kraus Antenna book And Balanis Antennas Complementary Antennas Dipole Slot Stub and slot look at currents Dipole Current and Voltage Distribution Voltage ID: 1017875
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1. Slot, Horn and Complementary AntennasEEE 212Figures are from Kraus’ Antenna bookAnd Balanis’ Antennas
2. Complementary AntennasDipole Slot
3. Stub and slot – look at currents
4. Dipole Current and Voltage DistributionVoltageCurrent
5. Slot Current and Voltage DistributionVoltageCurrent
6. Slot antenna feeds
7. Vertically and Horizontally polarized slots Sheet with slot radiates equally on both sides of the sheet.
8. Boxed-In SlotRadiates only from one side
9. Waveguide-Fed SlotRadiation only from one side
10. Slotted Waveguide
11. Complementary AntennasSlot and Dipole
12. Radiation Patterns of Slot and Dipole
13. Complementary AntennasDipoleSlothttps://www.feko.info/applications/white-papers/microstrip-fed-slot-antenna/microstrip-fed-slot-antenna/viewhttp://www.cisco.com/c/en/us/products/collateral/wireless/aironet-antennas-accessories/prod_white_paper0900aecd806a1a3e.html
14. Babinet’s PrincipleSlot antenna problems can be reduced to solving complementary wire antennas
15. Babinet’s PrincipleIt also holds when there’s diffraction.The field at any point behind the plane having a screen if added to the field at the same point when the complementary screen is substituted is equal to the field at the point when no screen is present.
16. Booker’s extension of Babinet’s principleBabinet’s principle is extended by Booker to take into account vector nature of EM Field.If the screen is perfectly conducting, the complementary screen has infinite permeabilityMetals are good conductors, but there’s no perfectly permeable materials -> equivalently use metal but interchange electric and magnetic fields everywhere
17. Booker’s ExtensionDipole is vertical because we’re interchanging electric and magnetic fieldsBabinet’s principle:
18. Impedance of complementary screensWe will look at Babinet’s principle applicationPropagation of waves through space can be represented by a transmission-line analogyImpedance of the line is 377OhmsImpedance of screen is Y1Impedance of complementary screen is Y2
19. Impedance of Screen
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22. Impedance of Complementary ScreenBabinet’s Principle ->
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24. If the input impedance of a dipole is Zd, find the impedance of the slot
25. If the input impedance of a dipole is Zd, find the impedance of the slot
26. Examples
27. Another example
28. Horn antennasEEE 212
29. Horn AntennasAre flared-out waveguidesThey produce uniform phase front with a larger aperture -> higher directivityDr. Bose constructed a pyramidal horn in 1897
30. Sir Jagadish Chandra Bose1858-1937
31. The receiver (left) used a galena point contact crystal rectifier inside the horn antenna and a galvanometer to detect the waves.60GHz Receiver and Transmitter used by Sir Jagadish Chandra Bose in Bose Institute, Kolkata
32. Types of Horn Antennas
33. Types of Horn Antennas
34. The fields at the aperture of the E-plane sectoral hornExpressions are similar to the field distribution of a waveguide, except quadratic phase term. The necessity of the quadratic term can be illustrated geometrically.
35. Quadratic Phase TermWe assume that the cylindrical waves are radiated from a wire at the apex of the apertureThe constant phase fronts are cylindricalThe phase at the aperture varies because the wave has traveled different distances from the apex to the apertureThe difference in path of travel can be obtained from the geometry
36. HornWe look at the horn’s cross-sectionDeviation from constant phaseHorn Length as a function of phase deviationHorn Flare angle as a function of phase deviation
37. HornWe look at the horn’s cross-section
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41. Comparison of rectangular horn patternsDonald Rhodes experimentally investigated horn patterns as a function of radial length RFlare angle
42. Experimentally obtained optimum dimensions of rectangular hornFrom Rhode’s experiments optimal dimensions were selected for E and H flare as a function of flare angle
43. Rectangular Horn patternsMinor lobesMinor lobesDue to E-field distribution in E and H plane
44. Types of Horn Antennas
45. Types of Horn Antennas
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47. Radiated Field of an E-plane sectorial horn
48. 3D Pattern of E-plane Sectoral HornE-plane narrower than H-plane
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50. Normalized pattern in E-planeC, S are Fresnel Integrals, tabulated in Appendix IV, Balanis
51. E and H plane patterns of an E-plane sectoral horn
52. Find normalized E-field intensity for any E-plane sectoral hornDetermine value of s from given b1 and rho1Search for that s on the next figure and find the strength of the electric fieldAdd 20log10[(1+cos )/2]
53. E-plane universal patterns for E-plane sectoral and pyramidal horns
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56. E and H plane patterns of an E-plane sectoral horn
57. Directivity of E-plane sectoral horn13.9c
58. Normalized Directivity of E-plane Sectoral Horn
59. Another Way to Calculate Directivity of E-plane sectoral horn
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65. Pyramidal Horn
66. Pyramidal Horn E-plane
67. Pyramidal Horn H-plane
68. Pyramidal Horn 3-D Pattern
69. Radiation Pattern E-plane
70. Radiation Pattern H-plane
71. Pyramidal Horn Construction
72. Pyramidal Horn Directivity
73. Pyramidal Horn Directivity
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81. Homework13.213.313.21