What is the approximate maximum separation measured along the surface of the Earth between two stations communicating by EME?

  1. 500 miles, if the moon is at perigee
  2. 2000 miles, if the moon is at apogee
  3. 5000 miles, if the moon is at perigee
  4. 12,000 miles, if the moon is visible by both stations


What characterizes libration fading of an EME signal?

  1. A slow change in the pitch of the CW signal
  2. A fluttery irregular fading
  3. A gradual loss of signal as the sun rises
  4. The returning echo is several hertz lower in frequency than the transmitted signal


When scheduling EME contacts, which of these conditions will generally result in the least path loss?

  1. When the moon is at perigee
  2. When the moon is full
  3. When the moon is at apogee
  4. When the MUF is above 30 MHz


What do Hepburn maps predict?

  1. Sporadic E propagation
  2. Locations of auroral reflecting zones
  3. Likelihood of rain scatter along cold or warm fronts
  4. Probability of tropospheric propagation


Tropospheric propagation of microwave signals often occurs in association with what phenomenon?

  1. Grayline
  2. Lightning discharges
  3. Warm and cold fronts
  4. Sprites and jets


What might help to restore contact when DX signals become too weak to copy across an entire HF band a few hours after sunset?

  1. Switch to a higher frequency HF band
  2. Switch to a lower frequency HF band
  3. Wait 90 minutes or so for the signal degradation to pass
  4. Wait 24 hours before attempting another communication on the band


Atmospheric ducts capable of propagating microwave signals often form over what geographic feature?

  1. Mountain ranges
  2. Forests
  3. Bodies of water
  4. Urban areas


When a meteor strikes the Earth's atmosphere, a cylindrical region of free electrons is formed at what layer of the ionosphere?

  1. The E layer
  2. The F1 layer
  3. The F2 layer
  4. The D layer


Which of the following frequency ranges is most suited for meteor scatter communications?

  1. 1.8 MHz - 1.9 MHz
  2. 10 MHz - 14 MHz
  3. 28 MHz - 148 MHz
  4. 220 MHz - 450 MHz


Which type of atmospheric structure can create a path for microwave propagation?

  1. The jet stream
  2. Temperature inversion
  3. Wind shear
  4. Dust devil


What is a typical range for tropospheric propagation of microwave signals?

  1. 10 miles to 50 miles
  2. 100 miles to 300 miles
  3. 1200 miles
  4. 2500 miles


What is the cause of auroral activity?

  1. The interaction in the F2 layer between the solar wind and the Van Allen belt
  2. An extreme low-pressure area in the polar regions
  3. The interaction in the E layer of charged particles from the Sun with the Earth's magnetic field
  4. Meteor showers concentrated in the extreme northern and southern latitudes


Which of these emission modes is best for auroral propagation?

  1. CW
  2. SSB
  3. FM
  4. RTTY


What is meant by circularly polarized electromagnetic waves?

  1. Waves with an electric field bent into a circular shape
  2. Waves with a rotating electric field
  3. Waves that circle the Earth
  4. Waves produced by a loop antenna