2016-E3A: Electromagnetic waves; Earth-Moon-Earth communications; meteor scatter; microwave tropospheric and scatter propagation; aurora propagation
What is the approximate maximum separation measured along the surface of the Earth between two stations communicating by Moon bounce?
12,000 miles, if the Moon is visible by both stations
500 miles, if the Moon is at perigee
2000 miles, if the Moon is at apogee
5000 miles, if the Moon is at perigee
What characterizes libration fading of an EME signal?
A fluttery irregular fading
A slow change in the pitch of the CW signal
A gradual loss of signal as the Sun rises
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?
When the Moon is at perigee
When the Moon is full
When the Moon is at apogee
When the MUF is above 30 MHz
What do Hepburn maps predict?
Probability of tropospheric propagation
Sporadic E propagation
Locations of auroral reflecting zones
Likelihood of rain-scatter along cold or warm fronts
Tropospheric propagation of microwave signals often occurs along what weather related structure?
Warm and cold fronts
Sprites and jets
Which of the following is required for microwave propagation via rain scatter?
The rain must be within radio range of both stations
Rain droplets must be electrically charged
Rain droplets must be within the E layer
All of these choices are correct
Atmospheric ducts capable of propagating microwave signals often form over what geographic feature?
Bodies of water
When a meteor strikes the Earth's atmosphere, a cylindrical region of free electrons is formed at what layer of the ionosphere?
The E layer
The F1 layer
The F2 layer
The D layer
Which of the following frequency range is most suited for meteor scatter communications?
28 MHz - 148 MHz
1.8 MHz - 1.9 MHz
10 MHz - 14 MHz
220 MHz - 450 MHz
Which type of atmospheric structure can create a path for microwave propagation?
The jet stream
What is a typical range for tropospheric propagation of microwave signals?
100 miles to 300 miles
10 miles to 50 miles
What is the cause of auroral activity?
The interaction in the E layer of charged particles from the Sun with the Earth's magnetic field
The interaction in the F2 layer between the solar wind and the Van Allen belt
A low sunspot level combined with tropospheric ducting
Meteor showers concentrated in the extreme northern and southern latitudes
Which emission mode is best for aurora propagation?
From the contiguous 48 states, in which approximate direction should an antenna be pointed to take maximum advantage of aurora propagation?
What is an electromagnetic wave?
A wave consisting of an electric field and a magnetic field oscillating at right angles to each other
A wave of alternating current, in the core of an electromagnet
A wave consisting of two electric fields at parallel right angles to each other
A wave consisting of two magnetic fields at right angles to each other
Which of the following best describes electromagnetic waves traveling in free space?
Changing electric and magnetic fields propagate the energy
Electric and magnetic fields become aligned as they travel
The energy propagates through a medium with a high refractive index
The waves are reflected by the ionosphere and return to their source
What is meant by circularly polarized electromagnetic waves?
Waves with a rotating electric field
Waves with an electric field bent into a circular shape
Waves that circle the Earth
Waves produced by a loop antenna
● = Unseen
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● = Incorrect answer