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Assignment 18

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

 1. 

T3A03 What antenna polarization is normally used for long-distance weak-signal CW and SSB contacts using the VHF and UHF bands?
a.
Right-hand circular
c.
Horizontal
b.
Left-hand circular
d.
Vertical
 

 2. 

T3A04 What can happen if the antennas at opposite ends of a VHF or UHF line of sight radio link are not using the same polarization?
a.
The modulation sidebands might become inverted
c.
Signals have an echo effect on voices
b.
Signals could be significantly weaker
d.
Nothing significant will happen
 

 3. 

T8C01 Which of the following methods is used to locate sources of noise interference or jamming?
a.
Echolocation
c.
Radio direction finding
b.
Doppler radar
d.
Phase locking
 

 4. 

T8C02 Which of these items would be useful for a hidden transmitter hunt?
a.
Calibrated SWR meter
c.
A calibrated noise bridge
b.
A directional antenna
d.
All of these choices are correct
 

 5. 

T9A01 What is a beam antenna?
a.
An antenna built from aluminum I-beams
c.
An antenna that concentrates signals in one direction
b.
An omnidirectional antenna invented by Clarence Beam
d.
An antenna that reverses the phase of received signals
 

 6. 

T9A02 Which of the following is true regarding vertical antennas?
a.
The magnetic field is perpendicular to the Earth
c.
The phase is inverted
b.
The electric field is perpendicular to the Earth
d.
The phase is reversed
 

 7. 

T9A03 Which of the following describes a simple dipole mounted so the conductor is parallel to the Earth's surface?
a.
A ground wave antenna
c.
A rhombic antenna
b.
A horizontally polarized antenna
d.
A vertically polarized antenna
 

 8. 

T9A05 How would you change a dipole antenna to make it resonant on a higher frequency?
a.
Lengthen it
c.
Shorten it
b.
Insert coils in series with radiating wires
d.
Add capacitive loading to the ends of the radiating wires
 

 9. 

T9A06 What type of antennas are the quad, Yagi, and dish?
a.
Non-resonant antennas
c.
Directional antennas
b.
Loop antennas
d.
Isotropic antennas
 

 10. 

T9A08 What is the approximate length, in inches, of a quarter-wavelength vertical antenna for 146 MHz?
a.
112
c.
19
b.
50
d.
12
 

 11. 

T9A09 What is the approximate length, in inches, of a 6 meter 1/2-wavelength wire dipole antenna?
a.
6
c.
112
b.
50
d.
236
 

 12. 

T9A10 In which direction is the radiation strongest from a half-wave dipole antenna in free space?
a.
Equally in all directions
c.
Broadside to the antenna
b.
Off the ends of the antenna
d.
In the direction of the feed line
 

 13. 

T9A11 What is meant by the gain of an antenna?
a.
The additional power that is added to the transmitter power
c.
The increase in signal strength in a specified direction when compared to a reference antenna
b.
The additional power that is lost in the antenna when transmitting on a higher frequency
d.
The increase in impedance on receive or transmit compared to a reference antenna
 

 14. 

T9A12 What is a reason to use a properly mounted 5/8 wavelength antenna for VHF or UHF mobile service?
a.
It offers a lower angle of radiation and more gain than a 1/4 wavelength antenna and usually provides improved coverage
c.
The 5/8 wavelength antenna completely eliminates distortion caused by reflected signals
b.
It features a very high angle of radiation and is better for communicating via a repeater
d.
The 5/8 wavelength antenna offers a 10-times power gain over a 1/4 wavelength design
 

 15. 

T9A13 Why are VHF or UHF mobile antennas often mounted in the center of the vehicle roof?
a.
Roof mounts have the lowest possible SWR of any mounting configuration
c.
A roof mounted antenna normally provides the most uniform radiation pattern
b.
Only roof mounting can guarantee a vertically polarized signal
d.
Roof mounted antennas are always the easiest to install
 

 16. 

T9A14 Which of the following terms describes a type of loading when referring to an antenna?
a.
Inserting an inductor in the radiating portion of the antenna to make it electrically longer
c.
Installing a spring at the base of the antenna to absorb the effects of collisions with other objects
b.
Inserting a resistor in the radiating portion of the antenna to make it resonant
d.
Making the antenna heavier so it will resist wind effects when in motion
 



 
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