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

 

T9A – Antennas: vertical and horizontal polarization; concept of gain; common portable and mobile antennas; relationships between resonant length and frequency; concept of dipole antennas 

 

 

T9A01 

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 

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T9A02 

Which of the following describes a type of antenna loading? 

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 in the base of a mobile vertical antenna to make it more flexible 

D. Strengthening the radiating elements of a beam antenna to better resist wind damage 

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T9A03 

Which of the following describes a simple dipole oriented 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 

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T9A04 

What is a disadvantage of the “rubber duck” antenna supplied with most handheld radio transceivers when compared to a full-sized quarter-wave antenna? 

A. It does not transmit or receive as effectively 

B. It transmits only circularly polarized signals 

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

D. All of these choices are correct 

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T9A05 

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 

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T9A06 

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

A. Non-resonant antennas 

B. Log periodic antennas 

C. Directional antennas 

D. Isotropic antennas 

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T9A07 

What is a disadvantage of using a handheld VHF transceiver, with its integral antenna, inside a vehicle? 

A. Signals might not propagate well due to the shielding effect of the vehicle 

B. It might cause the transceiver to overheat 

C. The SWR might decrease, decreasing the signal strength 

D. All of these choices are correct 

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T9A08 

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

A. 112 

B. 50 

C. 19 

D. 12 

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T9A09 

What is the approximate length, in inches, of a half-wavelength 6 meter dipole antenna? 

A. 6 

B. 50 

C. 112 

D. 236 

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T9A10 

In which direction does a half-wave dipole antenna radiate the strongest signal? 

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 

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T9A11 

What is 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 compared to a reference antenna 

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

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T9A12 

What is an advantage of using a properly mounted 5/8 wavelength antenna for VHF or UHF mobile service? 

A. It has a lower radiation angle and more gain than a 1/4 wavelength antenna 

B. It has very high angle radiation for better communicating through a repeater 

C. It eliminates distortion caused by reflected signals 

D. It has 10 times the power gain of a 1/4 wavelength design 

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T9B – Feed lines: types, attenuation vs frequency, selecting; SWR concepts; Antenna tuners (couplers); RF Connectors: selecting, weather protection  

 

 

 

T9B01 

Why is it important to have low SWR when using coaxial cable feed line? 

A. To reduce television interference 

B. To reduce signal loss 

C. To prolong antenna life 

D. All of these choices are correct 

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​

 

T9B02

What is the impedance of most coaxial cables used in amateur radio installations? 

A. 8 ohms 

B. 50 ohms 

C. 600 ohms 

D. 12 ohms 

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T9B03 

Why is coaxial cable the most common feed line selected 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 type of feed line 

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T9B04 

What is the major function of an antenna tuner (antenna coupler)? 

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 

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​

 

T9B05 

In general, what happens as the frequency of a signal passing through coaxial cable is increased? 

A. The characteristic impedance decreases 

B. The loss decreases 

C. The characteristic impedance increases 

D. The loss increases 

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​

 

T9B06 

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 

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T9B07 

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

A. They are preferred for microwave operation 

B. They are watertight 

C. They are commonly used at HF frequencies 

D. They are a bayonet type connector 

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T9B08 

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 

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T9B09 

What can 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 

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​

 

T9B10 

What is the electrical difference between RG-58 and RG-8 coaxial cable? 

A. There is no significant difference between the two types 

B. RG-58 cable has two shields 

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

D. RG-58 cable can handle higher power levels 

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​

 

T9B11 

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 

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