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Amateur Radio - Technician > T9 - Antennas and feed lines [2 Exam Questions - 2 Groups] > Flashcards

T9 - Antennas and feed lines [2 Exam Questions - 2 Groups] Flashcards

1
Q

What is a beam antenna?

A. An antenna built from aluminum I-beams

B. An omnidirectional antenna invented by Clarence Beam

C. An antenna that concentrates signals in one direction

D. An antenna that reverses the phase of received signals

A

C. An antenna that concentrates signals in one direction

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2
Q

Which of the following is true regarding vertical antennas?

A. The magnetic field is perpendicular to the Earth

B. The electric field is perpendicular to the Earth

C. The phase is inverted

D. The phase is reversed

A

B. The electric field is perpendicular to the Earth

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3
Q

Which of the following describes a simple dipole mounted so the conductor is parallel to the Earth’s surface?

A. A ground wave antenna

B. A horizontally polarized antenna

C. A rhombic antenna

D. A vertically polarized antenna

A

B. A horizontally polarized antenna

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4
Q

What is a disadvantage of the ‘‘rubber duck’’ antenna supplied with most handheld radio transceivers?

A. It does not transmit or receive as effectively as a full-sized antenna

B. It transmits a circularly polarized signal

C. If the rubber end cap is lost it will unravel very quickly

D. All of these choices are correct

A

A. It does not transmit or receive as effectively as a full-sized antenna

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5
Q

How would you change a dipole antenna to make it resonant on a higher frequency?

A. Lengthen it

B. Insert coils in series with radiating wires

C. Shorten it

D. Add capacitive loading to the ends of the radiating wires

A

C. Shorten it

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6
Q

What type of antennas are the quad, Yagi, and dish?

A. Non-resonant antennas

B. Loop antennas

C. Directional antennas

D. Isotropic antennas

A

C. Directional antennas

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7
Q

What is a good reason not to use a ‘‘rubber duck’’ antenna inside your car?

A. Signals can be significantly weaker than when it is outside of the vehicle

B. It might cause your radio to overheat

C. The SWR might decrease, decreasing the signal strength

D. All of these choices are correct

A

A. Signals can be significantly weaker than when it is outside of the vehicle

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8
Q

What is the approximate length, in inches, of a quarter-wavelength vertical antenna for 146 MHz?

A. 112

B. 50

C. 19

D. 12

A

C. 19

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9
Q

What is the approximate length, in inches, of a 6 meter 1/2-wavelength wire dipole antenna?

A. 6

B. 50

C. 112

D. 236

A

C. 112

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10
Q

In which direction is the radiation strongest from a half-wave dipole antenna in free space?

A. Equally in all directions

B. Off the ends of the antenna

C. Broadside to the antenna

D. In the direction of the feed line

A

C. Broadside to the antenna

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11
Q

What is meant by the gain of an antenna?

A. The additional power that is added to the transmitter power

B. The additional power that is lost in the antenna when transmitting on a higher frequency

C. The increase in signal strength in a specified direction when compared to a reference antenna

D. The increase in impedance on receive or transmit compared to a reference antenna

A

C. The increase in signal strength in a specified direction when compared to a reference antenna

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12
Q

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

B. It features a very high angle of radiation and is better for communicating via a repeater

C. The 5/8 wavelength antenna completely eliminates distortion caused by reflected signals

D. The 5/8 wavelength antenna offers a 10-times power gain over a 1/4 wavelength design

A

A. It offers a lower angle of radiation and more gain than a 1/4 wavelength antenna and usually provides improved coverage

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13
Q

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

B. Only roof mounting can guarantee a vertically polarized signal

C. A roof mounted antenna normally provides the most uniform radiation pattern

D. Roof mounted antennas are always the easiest to install

A

C. A roof mounted antenna normally provides the most uniform radiation pattern

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14
Q

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

B. Inserting a resistor in the radiating portion of the antenna to make it resonant

C. Installing a spring at the base of the antenna to absorb the effects of collisions with other objects

D. Making the antenna heavier so it will resist wind effects when in motion

A

A. Inserting an inductor in the radiating portion of the antenna to make it electrically longer

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15
Q

Why is it important to have a low SWR in an antenna system that uses coaxial cable feed line?

A. To reduce television interference

B. To allow the efficient transfer of power and reduce losses

C. To prolong antenna life

D. All of these choices are correct

A

B. To allow the efficient transfer of power and reduce losses

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16
Q

What is the impedance of the most commonly used coaxial cable in typical amateur radio installations?

A. 8 ohms

B. 50 ohms

C. 600 ohms

D. 12 ohms

A

B. 50 ohms

17
Q

Why is coaxial cable used more often than any other feed line for amateur radio antenna systems?

A. It is easy to use and requires few special installation considerations

B. It has less loss than any other type of feed line

C. It can handle more power than any other type of feed line

D. It is less expensive than any other types of feed line

A

A. It is easy to use and requires few special installation considerations

18
Q

What does an antenna tuner do?

A. It matches the antenna system impedance to the transceiver’s output impedance

B. It helps a receiver automatically tune in weak stations

C. It allows an antenna to be used on both transmit and receive

D. It automatically selects the proper antenna for the frequency band being used

A

A. It matches the antenna system impedance to the transceiver’s output impedance

19
Q

What generally happens as the frequency of a signal passing through coaxial cable is increased?

A. The apparent SWR increases

B. The reflected power increases

C. The characteristic impedance increases

D. The loss increases

A

D. The loss increases

20
Q

Which of the following connectors is most suitable for frequencies above 400 MHz?

A. A UHF (PL-259/SO-239) connector

B. A Type N connector

C. An RS-213 connector

D. A DB-25 connector

A

B. A Type N connector

21
Q

Which of the following is true of PL-259 type coax connectors?

A. They are preferred for microwave operation

B. They are water tight

C. They are commonly used at HF frequencies

D. They are a bayonet type connector

A

C. They are commonly used at HF frequencies

22
Q

Why should coax connectors exposed to the weather be sealed against water intrusion?

A. To prevent an increase in feed line loss

B. To prevent interference to telephones

C. To keep the jacket from becoming loose

D. All of these choices are correct

A

A. To prevent an increase in feed line loss

23
Q

What might cause erratic changes in SWR readings?

A. The transmitter is being modulated

B. A loose connection in an antenna or a feed line

C. The transmitter is being over-modulated

D. Interference from other stations is distorting your signal

A

B. A loose connection in an antenna or a feed line

24
Q

What electrical difference exists between the smaller RG-58 and larger RG-8 coaxial cables?

A. There is no significant difference between the two types

B. RG-58 cable has less loss at a given frequency

C. RG-8 cable has less loss at a given frequency

D. RG-58 cable can handle higher power levels

A

C. RG-8 cable has less loss at a given frequency

25
Q

Which of the following types of feed line has the lowest loss at VHF and UHF?

A. 50-ohm flexible coax

B. Multi-conductor unbalanced cable

C. Air-insulated hard line

D. 75-ohm flexible coax

A

C. Air-insulated hard line

Amateur Radio - Technician (10 decks)

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