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Subelement B-007

B-007

Section B-007-007

Section B-007-007

Which ionospheric region most affects sky-wave propagation on the 6-metre band?

  • The D region
  • Correct Answer
    The E region
  • The F1 region
  • The F2 region

At 50 MHz to 54 MHz, a 6-metre signal normally escapes into space. However, 'Sporadic E' ( intense but temporary ionization of patches in the upper reaches of the E region ) can provide refraction paths for 6 metres.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

What effect does tropospheric bending have on 2-metre radio waves?

  • Correct Answer
    It lets you contact stations farther away
  • It distorts the signal
  • It causes them to travel shorter distances
  • It interferes with short-range communications

Key word: BENDING. Tropospheric bending : refraction occurs when a wave travels through masses of differing densities (humidity content) in the troposphere. The wave travels further rather than escape right away into space.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

What causes tropospheric ducting of radio waves?

  • An aurora to the north
  • Correct Answer
    A temperature inversion
  • Lightning between the transmitting and receiving stations
  • A very low-pressure area

Key word: DUCTING. Wave gets caught (like in a waveguide) between sandwiched masses of different humidity contents. A 'temperature inversion', where hot air masses find themselves riding over cooler air, leads to conditions supporting 'Ducting'. Except for 'Tropo Ducting', common troposcatter (scattering through the troposphere) opens VHF paths out to 500 km for well-equipped stations (800 at the most). 'Tropospheric Ducting' permits distances beyond 800 km.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

What term describes that portion of a transmitted wave kept close to the Earth's surface due to bending in the atmosphere?

  • Ground wave
  • Ionospheric wave
  • Correct Answer
    Tropospheric wave
  • Scattered wave

Key word: BENDING. Tropospheric bending : refraction occurs when a wave travels through masses of differing densities (humidity content) in the troposphere. The wave travels further rather than escape right away into space.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

What is a sporadic-E condition?

  • Correct Answer
    Patches of dense ionization at E-region height
  • A brief decrease in VHF signals caused by sunspot variations
  • Variations in E-region height caused by sunspot variations
  • Occasional duct formation in the E region

At 50 MHz to 54 MHz, a 6-metre signal normally escapes into space. However, 'Sporadic E' ( intense but temporary ionization of patches in the upper reaches of the E region ) can provide refraction paths for 6 metres.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

On which amateur radio band is the extended-distance propagation effect of sporadic-E most often observed?

  • Correct Answer
    6 metres
  • 2 metres
  • 20 metres
  • 160 metres

At 50 MHz to 54 MHz, a 6-metre signal normally escapes into space. However, 'Sporadic E' ( intense but temporary ionization of patches in the upper reaches of the E region ) can provide refraction paths for 6 metres.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

In the northern hemisphere, in which direction should a directional antenna be pointed to take maximum advantage of auroral propagation?

  • West
  • South
  • East
  • Correct Answer
    North

Key word: AURORA. The arrival of high-energy particles from the Sun (e.g., after a solar flare) disturbs the Earth's magnetic field (a geomagnetic storm). The resulting unusual ionization of gases in the E region above the poles produces the visual display known as 'aurora' ("Northern Lights"). Pointing antennas at the aurora front permit oblique paths to distant stations through back scattering.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

Where in the ionosphere does auroral activity occur?

  • At D-region height
  • At F-region height
  • Correct Answer
    At E-region height
  • In the equatorial band

Key word: AURORA. The arrival of high-energy particles from the Sun (e.g., after a solar flare) disturbs the Earth's magnetic field (a geomagnetic storm). The resulting unusual ionization of gases in the E region above the poles produces the visual display known as 'aurora' ("Northern Lights"). Pointing antennas at the aurora front permit oblique paths to distant stations through back scattering.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

Which analog emission mode is the most reliable in auroral propagation?

  • Correct Answer
    CW, because it is readable even when distorted
  • CW, because it resists fading
  • FM, because it is readable even when distorted
  • FM, because it resists fading

The unstable front of the ionized regions and the ensuing scattering of the radio wave make for distorted signals, only the smaller bandwidth signals are usable.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

Excluding enhanced propagation modes, what is the approximate range of normal VHF tropospheric propagation?

  • 1600 km
  • 3200 km
  • 2400 km
  • Correct Answer
    800 km

Common troposcatter (scattering through the troposphere) opens VHF paths out to 500 km for well-equipped stations (800 at the most). 'Tropospheric Ducting' (where a wave gets caught between sandwiched air masses during a 'temperature inversion') permits distances beyond 800 km.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

What effect is responsible for propagating a VHF signal over 800 km?

  • Ionospheric refraction
  • Faraday rotation
  • Correct Answer
    Tropospheric ducting
  • D-region refraction

Common troposcatter (scattering through the troposphere) opens VHF paths out to 500 km for well-equipped stations (800 at the most). 'Tropospheric Ducting' (where a wave gets caught between sandwiched air masses during a 'temperature inversion') permits distances beyond 800 km.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

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