Содержание
- 2. Tonight’s Topics… Introduction Receiving Basics RX Loops Elongated Terminated Loops EWE Antenna Flag Antenna Pennant Antenna
- 4. Why do we need separate TX and RX antennas? Because, they have different requirements: TX antennas
- 5. Antenna A Antenna B (+3dB gain vs Antenna A) Is Antenna B a better TX Antenna
- 6. Single 720-foot Beverage. Two 720-foot Beverages. Spaced 70 feet apart. Diagrams from ON4UN’s Low Band DXing
- 7. Gain single Beverage: -11.2 dBi Gain two Beverages (70-ft sp): -8.2 dBi So, a pair of
- 8. NO – nothing has been gained! The pattern is still practically identical Front/Back is the same
- 9. How much Negative Gain can we tolerate with RX antennas? Modern receivers are very sensitive. If
- 10. Noise The sum of all unidentified signals (thunderstorms, man-made, cosmic etc.). Requires its own presentation! RX
- 11. Receive Loop Antennas
- 12. Max Max Null Null Diagram from Joseph Carr’s Practical Antenna Handbook
- 14. Normal loop in free space Nulls “filled in” by nearby metal objects Diagram from Joseph Carr’s
- 15. Diagram from Joseph Carr’s Practical Antenna Handbook
- 16. Diagram from Joseph Carr’s Practical Antenna Handbook
- 17. Diagram from Joseph Carr’s Practical Antenna Handbook
- 18. Receive Loops Summary Pros Small, lightweight Easy to build Sharp null in 2 directions Cons Poor
- 19. Elongated Terminated Loops Include Ewe, Flag, Pennant and K9AY Terminated loop produces a cardioid pattern Depth
- 20. Theory of Operation Despite the shape, actually a pair of verticals Feedline on top and bottom
- 21. Ewe Antenna Diagram from ON4UN’s Low Band DXing
- 22. Ewe Antenna at KC4HW
- 23. Flag Antenna Diagram from ON4UN’s Low Band DXing
- 24. www.qsl.net/w7iuv/
- 25. Pennant Antenna Diagram from ON4UN’s Low Band DXing
- 26. Delta Ewe Antenna Diagram from ON4UN’s Low Band DXing
- 27. K9AY Antenna Diagram from ON4UN’s Low Band DXing
- 28. http://www.hard-core-dx.com/
- 29. http://www.hard-core-dx.com/
- 30. K9AY Switchbox Diagram from ON4UN’s Low Band DXing
- 31. K9AY Control Box Diagram from ON4UN’s Low Band DXing
- 32. Ground Diagram from ON4UN’s Low Band DXing
- 33. Photo from ON4UN’s Low Band DXing
- 34. Diagram from ON4UN’s Low Band DXing
- 35. Feeding Elongated Loops Impedances range from 500 Ohms in K9AY, to 950 Ohms in Deltas and
- 36. Transformation Low-Z High-Z 500 Ω to 75 Ω 2 passes (1 turn) 5 passes 500 Ω
- 37. Diagram from www.w8ji.com
- 38. Elongated Loop Summary Pros Small footprint Simplicity Can be phased to improve performance Much better than
- 39. The Beverage Antenna!
- 41. Diagram from Joseph Carr’s Practical Antenna Handbook
- 42. Influence of Length Following slide shows EZNEC results for a Beverage with following characteristics: 2 meters
- 43. 710 M -4.0 dBi 4.4 wl 535 M -4.7 dBi 3.3 wl 353 M -6.3 dBi
- 45. How High? Not as critical as many think General rule: Higher Beverages produce higher output Higher
- 46. Ground Quality The better the ground, the lower the output Ground quality has little impact on
- 47. Gain Curves Radiation Angle Curve Gain and Radiation Angle Diagram from ON4UN’s Low Band DXing
- 48. Wire Inefficient antenna anyway, so size not critical as long as it is physically strong enough
- 49. Theoretical Surge Impedance Z = 138 log 4h d Where: h = height of wire d
- 50. Termination Resistor Should be non-inductive Antenna will pick up TX power and lightning surges, so use
- 51. Photo from www.w8ji.com
- 52. Diagram from ON4UN’s Low Band DXing
- 53. Supports Metal, non-metallic – doesn’t matter as long as antenna is insulated Poles, fence posts, trees,
- 55. Photo from ON4UN’s Low Band DXing
- 56. Photo from www.w8ji.com
- 57. Photo from www.w8ji.com
- 58. Photo from www.w8ji.com
- 59. Parallel and Crossing Beverages Separate parallel Beverages by distance equal to their height above ground Separate
- 60. Photo from ON4UN’s Low Band DXing
- 62. Matching the Beverage Antenna Several different core material/turns combinations available Separate primary/secondary windings advisable I prefer
- 63. Winding Binocular Cores Pri Sec Pri Z Sec Z Passes Passes Ohm Ohm 4 10 75
- 64. Coax Can use 50 or 75 Ohm cable I prefer 75 Ohm cable Works very well
- 65. Grounds One 8-foot ground rod may suffice Will probably need two or more to stabilize the
- 66. Multiple Beverages from one Hub Diagram from ON4UN’s Low Band DXing
- 67. Two Directions from one Beverage Diagram from ON4UN’s Low Band DXing
- 68. Another Method… Diagram from ON4UN’s Low Band DXing
- 69. Phasing Beverage Antennas To improve directivity without using long antennas, can phase individual Beverages Two methods:
- 70. Broadside Phasing Narrows frontal lobe Front/Back remains the same Fed in phase Multiband Require wide spacing
- 71. End-Fire Phasing Greatly improves Front/Back directivity Front lobe remains much the same Spacing 5 meters Stagger
- 72. Photo from ON4UN’s Low Band DXing
- 73. Broadside Phasing End-Fire Phasing Diagrams from ON4UN’s Low Band DXing
- 74. Crossfire Phasing Simple end-fire feed system developed by W8JI Usable over several octaves Termination value =
- 75. Beverage Antennas at VO1NO/VE3 5 acres near Merrickville Dimensions ~ 650 x 320 feet 8 directions
- 79. North 000 (Asia, India) 180 (S. America) Terminating resistor/ Matching Xfmr combo
- 80. North 090 True (Africa) 270 Deg (W6, S Pacific) Terminating resistor/ Matching Xfmr combo
- 81. North 150 Deg (Caribbean, S America) 330 Deg (Japan, W. Aus) Terminating resistor/ Matching Xfmr combo
- 82. North 045 (Europe, N. Africa) 225 (W. Coast, NZ) Terminating resistor/ Matching Xfmr combo Signal combiner
- 83. North Terminating resistor/ Matching Xfmr combo
- 84. Property too small? Try a BOG (Beverage On Ground) Termination ~ 200 to 300 Ohms Need
- 85. Example of an urban beverage installation
- 86. For more Information… The “Bible”!! Also check the website of Tom Rauch, W8JI: http://www.w8ji.com Try the
- 87. Questions?
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