1. SUBELEMENT T3 Radio wave characteristics: properties of radio waves; propagation modes [3 Exam Questions - 3 Groups] 1 Radio Waves 2014

2. T3A - Radio wave characteristics: how a radio signal travels; fading; multipath; wavelength vs. penetration; antenna orientation T3B - Radio and electromagnetic wave properties: the electromagnetic spectrum; wavelength vs. frequency; velocity of electromagnetic waves; calculating wavelength T3C - Propagation modes: line of sight; sporadic E; meteor and auroral scatter and reflections; tropospheric ducting; F layer skip; radio horizon 2Radio Waves

3. HF Propagation  It is the unpredictable nature of HF propagation that makes the HF bands so much fun.  Long distance communication (DX) is accomplished by the reflection of radio waves by the ionosphere, the upper layers of the atmosphere ionized by ultraviolet radiation from the sun. 3Radio Waves

4. Solar Effects on the Atmosphere 4Radio Waves

5. Radio Propagation Propagation is the path radio waves travel from one station to another. Three basic types of propagation: Line of Sight. Ground Wave. Sky Wave. 5Radio Waves

6. Ground Wave Propagation Ground waves travel along the ground Higher power, farther travel 6Radio Waves

7. Sky Wave Propagation At HF frequencies radio waves can be reflected by the Ionosphere. At VHF and higher frequencies the waves usually pass through the ionosphere. 7 Radio Waves

8. Sporadic “E” Propagation Small areas of the “E” Region can become highly ionized Allows long distance sky-wave propagation on the VHF bands Most likely to occur on the 6 meter band in the summertime By its name, it is “sporadic”. 8- Radio Waves 2014

9. Solar Effects Sun Spots – Sunspots look darker because they’re cooler than surrounding areas but emit ultraviolet light that charge the Ionosphere. More sunspots mean improved upper HF and lower VHF propagation. Sun Spot Cycle – Sunspots tend to come and go from minimum to maximum to minimum in an 11 year cycle. Different cycles have different maximums. Solar Emissions – Electromagnetic emissions like ultraviolet and x-rays arrive at the earth in only 8 minutes. Particle emissions can take 20-40 hours to arrive at the earth where they are pulled to the poles by the earth’s magnetic field. Solar Rotation – The sun rotates every 28 days (a solar day ) 9 Radio Waves 9

10. Sunspots 10Radio Waves Sunspots peak during 11-year cycles. The higher the sunspot count, the more the atmosphere is ionized. Thus, higher sunspot counts support a higher Maximum Usable Frequency (MUF).

11. Propagation  Ionosphere Layers  The Atmosphere is divided into layers A,B,C,D,E,F  The Ionosphere consist of layers D, E, and F  The D layer absorbs low frequencies  The F layer typically reflects radio waves < 30 MHz  Refraction  E layer refraction can be 1200 miles  The higher altitude F layer refraction can be 2500 miles  Balancing Absorption and Refraction  D layer absorption defines Lowest Usable Frequency (LUF)  E and F layer refraction determine Maximum Usable Frequency (MUF) 11 Radio Waves

12. Solar Particles and the Magnetosphere  Solar particle emissions are largely deflected by the earth’s magnetic field. Some are drawn to the poles and generate auroras. 12 Radio Waves

13. Critical Angle 13 Radio Waves

14. Propagation Reflection and Multi-path Interference 14Radio Waves

15. Tropospheric Ducting Radio waves are refracted between the earth and transition in the duct. This is primarily a VHF phenomena and allows propagation for hundreds or thousands of miles. The 2m distance record is between California and Hawaii via a tropo duct Ducts can be formed during temperature inversions in very stable weather conditions. Ducts are common in the midwest and along the coast (over open water) during summer 15Radio Waves

16. T3A01 - What should you do if another operator reports that your station’s 2 meter signals were strong just a moment ago, but now they are weak or distorted A. Change the batteries in your radio to a different type B. Turn on the CTCSS tone C. Ask the other operator to adjust his squelch control D. Try moving a few feet or changing the direction of your antenna if possible, as reflections may be causing multi-path distortion 16Radio Waves

17. T3A01 - What should you do if another operator reports that your station’s 2 meter signals were strong just a moment ago, but now they are weak or distorted A. Change the batteries in your radio to a different type B. Turn on the CTCSS tone C. Ask the other operator to adjust his squelch control D. Try moving a few feet or changing the direction of your antenna if possible, as reflections may be causing multi-path distortion 17Radio Waves

18. T3A02 - Why are UHF signals often more effective from inside buildings than VHF signals? A. VHF signals lose power faster over distance B. The shorter wavelength allows them to more easily penetrate the structure of buildings C. This is incorrect; VHF works better than UHF inside buildings D. UHF antennas are more efficient than VHF antennas 18Radio Waves

19. T3A02 - Why are UHF signals often more effective from inside buildings than VHF signals? A. VHF signals lose power faster over distance B. The shorter wavelength allows them to more easily penetrate the structure of buildings C. This is incorrect; VHF works better than UHF inside buildings D. UHF antennas are more efficient than VHF antennas 19Radio Waves

20. T3A03 - What antenna polarization is normally used for long-distance weak-signal CW and SSB contacts using the VHF and UHF bands? A. Right-hand circular B. Left-hand circular C. Horizontal D. Vertical 20Radio Waves

21. T3A03 - What antenna polarization is normally used for long-distance weak-signal CW and SSB contacts using the VHF and UHF bands? A. Right-hand circular B. Left-hand circular C. Horizontal D. Vertical 21Radio Waves

22. T3A04 - What can happen if the antennas at opposite ends of a VHF or UHF line of sight radio link are not using the same polarization? A. The modulation sidebands might become inverted B. Signals could be significantly weaker C. Signals have an echo effect on voices D. Nothing significant will happen 22Radio Waves

23. T3A04 - What can happen if the antennas at opposite ends of a VHF or UHF line of sight radio link are not using the same polarization? A. The modulation sidebands might become inverted B. Signals could be significantly weaker C. Signals have an echo effect on voices D. Nothing significant will happen 23Radio Waves

24. T3A05 - When using a directional antenna, how might your station be able to access a distant repeater if buildings or obstructions are blocking the direct line of sight path? A.Change from vertical to horizontal polarization B.Try to find a path that reflects signals to the repeater C.Try the long path D. Increase the antenna SWR 24Radio Waves

25. T3A05 - When using a directional antenna, how might your station be able to access a distant repeater if buildings or obstructions are blocking the direct line of sight path? A.Change from vertical to horizontal polarization B.Try to find a path that reflects signals to the repeater C.Try the long path D. Increase the antenna SWR 25Radio Waves

26. T3A06 - What term is commonly used to describe the rapid fluttering sound sometimes heard from mobile stations that are moving while transmitting? A. Flip-flopping B. Picket fencing C. Frequency shifting D. Pulsing 26Radio Waves

27. T3A06 - What term is commonly used to describe the rapid fluttering sound sometimes heard from mobile stations that are moving while transmitting? A. Flip-flopping B. Picket fencing C. Frequency shifting D. Pulsing 27Radio Waves

28. T3A07 - What type of wave carries radio signals between transmitting and receiving stations? A. Electromagnetic B. Electrostatic C. Surface acoustic D. Magnetostrictive 28Radio Waves

29. T3A07 - What type of wave carries radio signals between transmitting and receiving stations? A. Electromagnetic B. Electrostatic C. Surface acoustic D. Magnetostrictive 29Radio Waves

30. T3A08 - Which of the following is a likely cause of irregular fading of signals received by ionospheric reflection? A. Frequency shift due to Faraday rotation B. Interference from thunderstorms C. Random combining of signals arriving via different paths D. Intermodulation distortion 30Radio Waves

31. T3A08 - Which of the following is a likely cause of irregular fading of signals received by ionospheric reflection? A. Frequency shift due to Faraday rotation B. Interference from thunderstorms C. Random combining of signals arriving via different paths D. Intermodulation distortion 31Radio Waves

32. T3A09 Which of the following results from the fact that skip signals refracted from the ionosphere are elliptically polarized? A. Digital modes are unusable B. Either vertically or horizontally polarized antennas may be used for transmission or reception C. FM voice is unusable D. Both the transmitting and receiving antennas must be of the same polarization 32Radio Waves

33. T3A09 Which of the following results from the fact that skip signals refracted from the ionosphere are elliptically polarized? A. Digital modes are unusable B. Either vertically or horizontally polarized antennas may be used for transmission or reception C. FM voice is unusable D. Both the transmitting and receiving antennas must be of the same polarization 33Radio Waves

34. T3A10 - What may occur if data signals propagate over multiple paths? A. Transmission rates can be increased by a factor equal to the number of separate paths observed B. Transmission rates must be decreased by a factor equal to the number of separate paths observed C. No significant changes will occur if the signals are transmitting using FM D. Error rates are likely to increase 34Radio Waves

35. T3A10 - What may occur if data signals propagate over multiple paths? A. Transmission rates can be increased by a factor equal to the number of separate paths observed B. Transmission rates must be decreased by a factor equal to the number of separate paths observed C. No significant changes will occur if the signals are transmitting using FM D. Error rates are likely to increase 35Radio Waves

36. T3A11 - Which part of the atmosphere enables the propagation of radio signals around the world? A. The stratosphere B. The troposphere C. The ionosphere D. The magnetosphere 36Radio Waves

37. T3A11 - Which part of the atmosphere enables the propagation of radio signals around the world? A. The stratosphere B. The troposphere C. The ionosphere D. The magnetosphere 37Radio Waves

38. T3B - Radio and electromagnetic wave properties the electromagnetic spectrum; wavelength vs. frequency; velocity of electromagnetic waves; calculating wavelength 38Radio Waves

39. Wavelength vs Frequency The distance a radio wave travels in one cycle is called wavelength The number of cycles per second is frequency The maximum displacement of wave from reference value is amplitude 39Radio Waves One Wavelength One Wavelength Time V+ V- 0V One Cycle Amplitude

40. T3B01 - What is the name for the distance a radio wave travels during one complete cycle? A. Wave speed B. Waveform C. Wavelength D. Wave spread 40Radio Waves

41. T3B01 - What is the name for the distance a radio wave travels during one complete cycle? A. Wave speed B. Waveform C. Wavelength D. Wave spread 41Radio Waves

42. T3B02 - What property of a radio wave is used to describe its polarization? A. The orientation of the electric field B. The orientation of the magnetic field C. The ratio of the energy in the magnetic field to the energy in the electric field D. The ratio of the velocity to the wavelength 42Radio Waves

43. T3B02 - What property of a radio wave is used to describe its polarization? A. The orientation of the electric field B. The orientation of the magnetic field C. The ratio of the energy in the magnetic field to the energy in the electric field D. The ratio of the velocity to the wavelength 43Radio Waves

44. T3B03 - What are the two components of a radio wave? A. AC and DC B. Voltage and current C. Electric and magnetic fields D. Ionizing and non-ionizing radiation 44Radio Waves

45. T3B03 - What are the two components of a radio wave? A. AC and DC B. Voltage and current C. Electric and magnetic fields D. Ionizing and non-ionizing radiation 45Radio Waves

46. T3B04 - How fast does a radio wave travel through free space? A. At the speed of light B. At the speed of sound C. Its speed is inversely proportional to its wavelength D. Its speed increases as the frequency increases 46Radio Waves

47. T3B04 - How fast does a radio wave travel through free space? A. At the speed of light B. At the speed of sound C. Its speed is inversely proportional to its wavelength D. Its speed increases as the frequency increases 47Radio Waves

48. Frequency to Wavelength Conversion To convert from frequency to wavelength in meters: 48Radio Waves 300 300 Freq ( MHz ) Wavelength = Frequency and wavelength are inversely proportional – as one increases, the other decreases Longer (wavelength) – Lower (frequency)

49. T3B05 - How does the wavelength of a radio wave relate to its frequency? A. The wavelength gets longer as the frequency increases B. The wavelength gets shorter as the frequency increases C. There is no relationship between wavelength and frequency D. The wavelength depends on the bandwidth of the signal 49Radio Waves

50. T3B05 - How does the wavelength of a radio wave relate to its frequency? A. The wavelength gets longer as the frequency increases B. The wavelength gets shorter as the frequency increases C. There is no relationship between wavelength and frequency D. The wavelength depends on the bandwidth of the signal 50Radio Waves

51. Frequency Calculations 300 is the Speed of Light in free space – Radio wave travel at the Speed of Light – 300,000,000 meters per second – Radio waves moves slower in wire – Velocity Factor is speed in a material divided by the speed of light i.e..66 f is frequency in millions (MHz) – The millions of cycles cancel the millions of meters – 146,520,000 = 146.53 MHz m is Wave length in Meters or the distance of a full cycle – How far it takes a wave to complete a complete cycle – The higher the frequency the lower the meter (shorter) – The lower the frequency the higher the meters (longer ) 51 Radio Waves 300 fm 300 = f x m

52. Frequency Calculations 52 300 fm 300,000,000 Frequency Wave length meters 300is the speed of light 300,000,000 meters per second Fis frequency in MHz Mis Wave Length distance in meters of a full cycle at this frequency To solve for a value, cover it with your finger and solve the remaining formula Radio Waves 2014

53. Frequency Calculations 53Electrical Principles 2014 300 f MHz m freq = 300/m

54. Meters Calculations 54Electrical Principles 2014 300 fm meters = 300/f

55. T3B06 - What is the formula for converting frequency to approximate wavelength in meters? A. Wavelength in meters equals frequency in hertz multiplied by 300 B. Wavelength in meters equals frequency in hertz divided by 300 C. Wavelength in meters equals frequency in megahertz divided by 300 D. Wavelength in meters equals 300 divided by frequency in megahertz 55Radio Waves

56. T3B06 - What is the formula for converting frequency to approximate wavelength in meters? A. Wavelength in meters equals frequency in hertz multiplied by 300 B. Wavelength in meters equals frequency in hertz divided by 300 C. Wavelength in meters equals frequency in megahertz divided by 300 D. Wavelength in meters equals 300 divided by frequency in megahertz 56Radio Waves

57. T3B07 - What property of radio waves is often used to identify the different frequency bands? A. The approximate wavelength B. The magnetic intensity of waves C. The time it takes for waves to travel one mile D. The voltage standing wave ratio of waves 57Radio Waves

58. T3B07 - What property of radio waves is often used to identify the different frequency bands? A. The approximate wavelength B. The magnetic intensity of waves C. The time it takes for waves to travel one mile D. The voltage standing wave ratio of waves 58Radio Waves One Wavelength One Wavelength Time V+ V-V-V-V- 0V One Cycle Amplitude

59. Radio Spectrum Medium Wave (MF) Short Wave (HF) Very High Frequency (VHF) Ultra High Frequency (UHF) 59Radio Waves AM Broadcast 540 1630 TV 2-6 54 88 FM Broadcast 108 TV 7-13 174 216 TV 14-69 470 806 300 kHz 3 MHz 30 MHz300 MHz3 GHz Frequency 1 Km 100 m 10 m 1 m10 cm Wavelength Major Amateur Bands in BLUE

60. T3B08 - What are the frequency limits of the VHF spectrum? A. 30 to 300 kHz B. 30 to 300 MHz C. 300 to 3000 kHz D. 300 to 3000 MHz 60Radio Waves

61. T3B08 - What are the frequency limits of the VHF spectrum? A. 30 to 300 kHz B. 30 to 300 MHz C. 300 to 3000 kHz D. 300 to 3000 MHz 61Radio Waves

62. T3B09 - What are the frequency limits of the UHF spectrum? A. 30 to 300 kHz B. 30 to 300 MHz C. 300 to 3000 kHz D. 300 to 3000 MHz 62Radio Waves

63. T3B09 - What are the frequency limits of the UHF spectrum? A. 30 to 300 kHz B. 30 to 300 MHz C. 300 to 3000 kHz D. 300 to 3000 MHz 63Radio Waves

64. T3B10 - What frequency range is referred to as HF? A. 300 to 3000 MHz B. 30 to 300 MHz C. 3 to 30 MHz D. 300 to 3000 kHz 64Radio Waves

65. T3B10 - What frequency range is referred to as HF? A. 300 to 3000 MHz B. 30 to 300 MHz C. 3 to 30 MHz D. 300 to 3000 kHz 65Radio Waves

66. T3B11 - What is the approximate velocity of a radio wave as it travels through free space? A. 3000 kilometers per second B. 300,000,000 meters per second C. 300,000 miles per hour D. 186,000 miles per hour 66Radio Waves

67. T3B11 - What is the approximate velocity of a radio wave as it travels through free space? A. 3000 kilometers per second B. 300,000,000 meters per second C. 300,000 miles per hour D. 186,000 miles per hour 67Radio Waves

68. T3C - Propagation modes line of sight; sporadic E; meteor and auroral scatter and reflections; tropospheric ducting; F layer skip; radio horizon 68Radio Waves

69. Aurora Borealis 69Radio Waves

70. T3C01 - Why are direct (not via a repeater) UHF signals rarely heard from stations outside your local coverage area? A. They are too weak to go very far B. FCC regulations prohibit them from going more than 50 miles C. UHF signals are usually not reflected by the ionosphere D. They collide with trees and shrubbery and fade out 70Radio Waves

71. T3C01 - Why are direct (not via a repeater) UHF signals rarely heard from stations outside your local coverage area? A. They are too weak to go very far B. FCC regulations prohibit them from going more than 50 miles C. UHF signals are usually not reflected by the ionosphere D. They collide with trees and shrubbery and fade out 71Radio Waves

72. T3C02 - Which of the following might be happening when VHF signals are being received from long distances? A. Signals are being reflected from outer space B. Signals are arriving by sub-surface ducting C. Signals are being reflected by lightning storms in your area D. Signals are being refracted from a sporadic E layer 72Radio Waves

73. T3C02 - Which of the following might be happening when VHF signals are being received from long distances? A. Signals are being reflected from outer space B. Signals are arriving by sub-surface ducting C. Signals are being reflected by lightning storms in your area D. Signals are being refracted from a sporadic E layer 73Radio Waves

74. T3C03 - What is a characteristic of VHF signals received via auroral reflection? A. Signals from distances of 10,000 or more miles are common B. The signals exhibit rapid fluctuations of strength and often sound distorted C. These types of signals occur only during winter nighttime hours D. These types of signals are generally strongest when your antenna is aimed west 74Radio Waves

75. T3C03 - What is a characteristic of VHF signals received via auroral reflection? A. Signals from distances of 10,000 or more miles are common B. The signals exhibit rapid fluctuations of strength and often sound distorted C. These types of signals occur only during winter nighttime hours D. These types of signals are generally strongest when your antenna is aimed west 75Radio Waves

76. T3C04 - Which of the following propagation types is most commonly associated with occasional strong over-the- horizon signals on the 10, 6, and 2 meter bands? A. Backscatter B. Sporadic E C. D layer absorption D. Gray-line propagation 76Radio Waves

77. T3C04 - Which of the following propagation types is most commonly associated with occasional strong over-the- horizon signals on the 10, 6, and 2 meter bands? A. Backscatter B. Sporadic E C. D layer absorption D. Gray-line propagation 77Radio Waves

78. T3C05 - Which of the following effects might cause radio signals to be heard despite obstructions between the transmitting and receiving stations? A. Knife-edge diffraction B. Faraday rotation C. Quantum tunneling D. Doppler shift 78Radio Waves

79. T3C05 - Which of the following effects might cause radio signals to be heard despite obstructions between the transmitting and receiving stations? A. Knife-edge diffraction B. Faraday rotation C. Quantum tunneling D. Doppler shift 79Radio Waves

80. T3C06 - What mode is responsible for allowing over-the- horizon VHF and UHF communications to ranges of approximately 300 miles on a regular basis? A. Tropospheric scatter B. D layer refraction C. F2 layer refraction D. Faraday rotation 80Radio Waves

81. T3C06 - What mode is responsible for allowing over-the- horizon VHF and UHF communications to ranges of approximately 300 miles on a regular basis? A. Tropospheric scatter B. D layer refraction C. F2 layer refraction D. Faraday rotation 81Radio Waves

82. T3C07 - What band is best suited for communicating via meteor scatter? A. 10 meters B. 6 meters C. 2 meters D. 70 cm 82Radio Waves

83. T3C07 - What band is best suited for communicating via meteor scatter? A. 10 meters B. 6 meters C. 2 meters D. 70 cm 83Radio Waves

84. T3C08 - What causes tropospheric ducting? A. Discharges of lightning during electrical storms B. Sunspots and solar flares C. Updrafts from hurricanes and tornadoes D. Temperature inversions in the atmosphere 84Radio Waves

85. T3C08 - What causes tropospheric ducting? A. Discharges of lightning during electrical storms B. Sunspots and solar flares C. Updrafts from hurricanes and tornadoes D. Temperature inversions in the atmosphere 85Radio Waves

86. T3C09 - What is generally the best time for long- distance 10 meter band propagation via the F layer? A. From dawn to shortly after sunset during periods of high sunspot activity B. From shortly after sunset to dawn during periods of high sunspot activity C. From dawn to shortly after sunset during periods of low sunspot activity D. From shortly after sunset to dawn during periods of low sunspot activity 86Radio Waves

87. T3C09 - What is generally the best time for long- distance 10 meter band propagation via the F layer? A. From dawn to shortly after sunset during periods of high sunspot activity B. From shortly after sunset to dawn during periods of high sunspot activity C. From dawn to shortly after sunset during periods of low sunspot activity D. From shortly after sunset to dawn during periods of low sunspot activity 87Radio Waves

88. T3C10 - What is the radio horizon? A. The distance over which two stations can communicate by direct path B. The distance from the ground to a horizontally mounted antenna C. The farthest point you can see when standing at the base of your antenna tower D. The shortest distance between two points on the Earth's surface 88Radio Waves

89. T3C10 - What is the radio horizon? A. The distance over which two stations can communicate by direct path B. The distance from the ground to a horizontally mounted antenna C. The farthest point you can see when standing at the base of your antenna tower D. The shortest distance between two points on the Earth's surface 89Radio Waves

90. T3C11 - Why do VHF and UHF radio signals usually travel somewhat farther than the visual line of sight distance between two stations? A. Radio signals move somewhat faster than the speed of light B. Radio waves are not blocked by dust particles C. The Earth seems less curved to radio waves than to light D. Radio waves are blocked by dust particles 90Radio Waves

91. T3C11 - Why do VHF and UHF radio signals usually travel somewhat farther than the visual line of sight distance between two stations? A. Radio signals move somewhat faster than the speed of light B. Radio waves are not blocked by dust particles C. The Earth seems less curved to radio waves than to light D. Radio waves are blocked by dust particles 91Radio Waves

92. T3C12 - Which of the following bands may provide long distance communications during the peak of the sunspot cycle? A. Six or ten meters B. 23 centimeters C. 70 centimeters or 1.25 meters D. All of these choices are correct 92Radio Waves

93. T3C12 - Which of the following bands may provide long distance communications during the peak of the sunspot cycle? A. Six or ten meters B. 23 centimeters C. 70 centimeters or 1.25 meters D. All of these choices are correct 93Radio Waves

94. Measuring the Sun Solar Flux – A measure of the sun’s noise at 10.7cm Solar K-index – The K-index quantifies disturbances in the horizontal component of earth's magnetic field during a 3 hour interval with an integer in the range 0-9 with 1 being calm and 5 or more indicating a geomagnetic storm. The K-index is a measure of short term stability of the Earth’s magnetic field. Solar A-index – The A-index provides a daily average level for geomagnetic activity and indicates long term stability of the Earth’s geomagnetic field. 94 Radio Waves 2014

95. G3A08 Which of the following effects can a geomagnetic storm have on radio-wave propagation? A. Improved high-latitude HF propagation B. Degraded high-latitude HF propagation C. Improved ground-wave propagation D. Improved chances of UHF ducting 95 Radio Waves 2014

96. G3A08 Which of the following effects can a geomagnetic storm have on radio-wave propagation? A. Improved high-latitude HF propagation B. Degraded high-latitude HF propagation C. Improved ground-wave propagation D. Improved chances of UHF ducting 96 Radio Waves 2014

97. G3A16 What is a possible benefit to radio communications resulting from periods of high geomagnetic activity? A. Aurora that can reflect VHF signals B. Higher signal strength for HF signals passing through the polar regions C. Improved HF long path propagation D. Reduced long delayed echoes 97 Radio Waves 2014

98. G3A16 What is a possible benefit to radio communications resulting from periods of high geomagnetic activity? A. Aurora that can reflect VHF signals B. Higher signal strength for HF signals passing through the polar regions C. Improved HF long path propagation D. Reduced long delayed echoes 98 Radio Waves 2014

99. G3B12 What factors affect the Maximum Usable Frequency (MUF)? A. Path distance and location B. Time of day and season C. Solar radiation and ionospheric disturbances D. All of these choices are correct 99 Radio Waves 2014

100. G3B12 What factors affect the Maximum Usable Frequency (MUF)? A. Path distance and location B. Time of day and season C. Solar radiation and ionospheric disturbances D. All of these choices are correct 100 Radio Waves 2014

101. Backscatter Propagation 101 Radio Waves 2014

102. G3C07 What makes HF scatter signals often sound distorted? A. The ionospheric layer involved is unstable B. Ground waves are absorbing much of the signal C. The E-region is not present D. Energy is scattered into the skip zone through several different radio wave paths 102 Radio Waves 2014

103. G3C07 What makes HF scatter signals often sound distorted? A. The ionospheric layer involved is unstable B. Ground waves are absorbing much of the signal C. The E-region is not present D. Energy is scattered into the skip zone through several different radio wave paths 103 Radio Waves 2014

104. End of SUBELEMENT T3 Radio wave characteristics: properties of radio waves; propagation modes 104Radio Waves