E3C-2012: Propagation and technique, Aurora propagation; selective fading; radio-path horizon; take-off angle over flat or sloping terrain; effects of ground on propagation; less common propagation modes
Which of the following effects does Aurora activity have on radio communications?
All of these choices are correct
SSB signals are raspy
Signals propagating through the Aurora are fluttery
CW signals appear to be modulated by white noise
What is the cause of Aurora activity?
The interaction of charged particles from the Sun with the Earth's magnetic field and the ionosphere
The interaction between the solar wind and the Van Allen belt
A low sunspot level combined with tropospheric ducting
Meteor showers concentrated in the northern latitudes
Where in the ionosphere does Aurora activity occur?
In the E-region
In the F1-region
In the F2-region
In the D-region
Which emission mode is best for Aurora propagation?
Which of the following describes selective fading?
Partial cancellation of some frequencies within the received pass band
Variability of signal strength with beam heading
Sideband inversion within the ionosphere
Degradation of signal strength due to backscatter
By how much does the VHF/UHF radio-path horizon distance exceed the geometric horizon?
By approximately 15% of the distance
By approximately twice the distance
By approximately one-half the distance
By approximately four times the distance
How does the radiation pattern of a horizontally polarized 3-element beam antenna vary with its height above ground?
The main lobe takeoff angle decreases with increasing height
The main lobe takeoff angle increases with increasing height
The horizontal beam width increases with height
The horizontal beam width decreases with height
What is the name of the high-angle wave in HF propagation that travels for some distance within the F2 region?
Which of the following is usually responsible for causing VHF signals to propagate for hundreds of miles?
How does the performance of a horizontally polarized antenna mounted on the side of a hill compare with the same antenna mounted on flat ground?
The main lobe takeoff angle decreases in the downhill direction
The main lobe takeoff angle increases in the downhill direction
The horizontal beam width decreases in the downhill direction
The horizontal beam width increases in the uphill direction
From the contiguous 48 states, in which approximate direction should an antenna be pointed to take maximum advantage of aurora propagation?
How does the maximum distance of ground-wave propagation change when the signal frequency is increased?
It stays the same
It peaks at roughly 14 MHz
What type of polarization is best for ground-wave propagation?
Why does the radio-path horizon distance exceed the geometric horizon?
Downward bending due to density variations in the atmosphere
Downward bending due to aurora refraction
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