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Assignment 10

Multiple Choice
Identify the choice that best completes the statement or answers the question.
 

 1. 

T3A08 Which of the following is a likely cause of irregular fading of signals received by ionospheric reflection?
a.
Frequency shift due to Faraday rotation
c.
Random combining of signals arriving via different paths
b.
Interference from thunderstorms
d.
Intermodulation distortion
 

 2. 

T3A09 Which of the following results from the fact that skip signals refracted from the ionosphere are elliptically polarized?
a.
Digital modes are unusable
c.
FM voice is unusable
b.
Either vertically or horizontally polarized antennas may be used for transmission or reception
d.
Both the transmitting and receiving antennas must be of the same polarization
 

 3. 

T3A11 Which part of the atmosphere enables the propagation of radio signals around the world?
a.
The stratosphere
c.
The ionosphere
b.
The troposphere
d.
The magnetosphere
 

 4. 

T3B02 What property of a radio wave is used to describe its polarization?
a.
The orientation of the electric field
c.
The ratio of the energy in the magnetic field to the energy in the electric field
b.
The orientation of the magnetic field
d.
The ratio of the velocity to the wavelength
 

 5. 

T3C01 Why are direct (not via a repeater) UHF signals rarely heard from stations outside your local coverage area?
a.
They are too weak to go very far
c.
UHF signals are usually not reflected by the ionosphere
b.
FCC regulations prohibit them from going more than 50 miles
d.
They collide with trees and shrubbery and fade out
 

 6. 

T3C02 Which of the following might be happening when VHF signals are being received from long distances?
a.
Signals are being reflected from outer space
c.
Signals are being reflected by lightning storms in your area
b.
Signals are arriving by sub-surface ducting
d.
Signals are being refracted from a sporadic E layer
 

 7. 

T3C03 What is a characteristic of VHF signals received via auroral reflection?
a.
Signals from distances of 10,000 or more miles are common
c.
These types of signals occur only during winter nighttime hours
b.
The signals exhibit rapid fluctuations of strength and often sound distorted
d.
These types of signals are generally strongest when your antenna is aimed west
 

 8. 

T3C04 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?
a.
Backscatter
c.
D layer absorption
b.
Sporadic E
d.
Gray-line propagation
 

 9. 

T3C05 Which of the following effects might cause radio signals to be heard despite obstructions between the transmitting and receiving stations?
a.
Knife-edge diffraction
c.
Quantum tunneling
b.
Faraday rotation
d.
Doppler shift
 

 10. 

T3C06 What mode is responsible for allowing over-the-horizon VHF and UHF communications to ranges of approximately 300 miles on a regular basis?
a.
Tropospheric scatter
c.
F2 layer refraction
b.
D layer refraction
d.
Faraday rotation
 

 11. 

T3C07 What band is best suited for communicating via meteor scatter?
a.
10 meters
c.
2 meters
b.
6 meters
d.
70 cm
 

 12. 

T3C08 What causes tropospheric ducting?
a.
Discharges of lightning during electrical storms
c.
Updrafts from hurricanes and tornadoes
b.
Sunspots and solar flares
d.
Temperature inversions in the atmosphere
 

 13. 

T3C09 What is generally the best time for long-distance 10 meter band propagation via the F layer?
a.
From dawn to shortly after sunset during periods of high sunspot activity
c.
From dawn to shortly after sunset during periods of low sunspot activity
b.
From shortly after sunset to dawn during periods of high sunspot activity
d.
From shortly after sunset to dawn during periods of low sunspot activity
 

 14. 

T3C10 What is the radio horizon?
a.
The distance over which two stations can communicate by direct path
c.
The farthest point you can see when standing at the base of your antenna tower
b.
The distance from the ground to a horizontally mounted antenna
d.
The shortest distance between two points on the Earth's surface
 

 15. 

T3C11 Why do VHF and UHF radio signals usually travel somewhat farther than the visual line of sight distance between two stations?
a.
Radio signals move somewhat faster than the speed of light
c.
The Earth seems less curved to radio waves than to light
b.
Radio waves are not blocked by dust particles
d.
Radio waves are blocked by dust particles
 

 16. 

T3C12 Which of the following bands may provide long distance communications during the peak of the sunspot cycle?
a.
Six or ten meters
c.
70 centimeters or 1.25 meters
b.
23 centimeters
d.
All of these choices are correct
 

 17. 

T5C07 What is a usual name for electromagnetic waves that travel through space?
a.
Gravity waves
c.
Radio waves
b.
Sound waves
d.
Pressure waves
 



 
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