Topic T3C Quick Review Audio


Why are direct (not via a repeater) UHF signals rarely heard from stations outside your local coverage area?

  1. They are too weak to go very far
  2. FCC regulations prohibit them from going more than 50 miles
  3. UHF signals are usually not reflected by the ionosphere
  4. UHF signals are absorbed by the ionospheric D layer


Which of the following is an advantage of HF vs VHF and higher frequencies?

  1. HF antennas are generally smaller
  2. HF accommodates wider bandwidth signals
  3. Long distance ionospheric propagation is far more common on HF
  4. There is less atmospheric interference (static) on HF


What is a characteristic of VHF signals received via auroral reflection?

  1. Signals from distances of 10,000 or more miles are common
  2. The signals exhibit rapid fluctuations of strength and often sound distorted
  3. These types of signals occur only during winter nighttime hours
  4. These types of signals are generally strongest when your antenna is aimed west


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?

  1. Backscatter
  2. Sporadic E
  3. D layer absorption
  4. Gray-line propagation


Which of the following effects might cause radio signals to be heard despite obstructions between the transmitting and receiving stations?

  1. Knife-edge diffraction
  2. Faraday rotation
  3. Quantum tunneling
  4. Doppler shift


What mode is responsible for allowing over-the-horizon VHF and UHF communications to ranges of approximately 300 miles on a regular basis?

  1. Tropospheric ducting
  2. D layer refraction
  3. F2 layer refraction
  4. Faraday rotation


What band is best suited for communicating via meteor scatter?

  1. 10 meter band
  2. 6 meter band
  3. 2 meter band
  4. 70 centimeter band


What causes tropospheric ducting?

  1. Discharges of lightning during electrical storms
  2. Sunspots and solar flares
  3. Updrafts from hurricanes and tornadoes
  4. Temperature inversions in the atmosphere


What is generally the best time for long-distance 10 meter band propagation via the F layer?

  1. From dawn to shortly after sunset during periods of high sunspot activity
  2. From shortly after sunset to dawn during periods of high sunspot activity
  3. From dawn to shortly after sunset during periods of low sunspot activity
  4. From shortly after sunset to dawn during periods of low sunspot activity


Which of the following bands may provide long distance communications during the peak of the sunspot cycle?

  1. 6 or 10 meter bands
  2. 23 centimeter band
  3. 70 centimeter or 1.25 meter bands
  4. All of these choices are correct


Why do VHF and UHF radio signals usually travel somewhat farther than the visual line of sight distance between two stations?

  1. Radio signals move somewhat faster than the speed of light
  2. Radio waves are not blocked by dust particles
  3. The Earth seems less curved to radio waves than to light
  4. Radio waves are blocked by dust particles