FCC Technician Class Exam Study Guide - 2014-2018/Subelement T9 Group A
Antennas: vertical and horizontal polarization; concept of gain; common portable and mobile antennas; relationships between antenna length and frequency
The Question Pool
[edit | edit source]Question 1
[edit | edit source]- 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
The correct answer is C.
Question 2
[edit | edit source]- 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
The correct answer is B.
Question 3
[edit | edit source]- 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
The correct answer is B.
Question 4
[edit | edit source]- 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
The correct answer is A.
Question 5
[edit | edit source]- 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
The correct answer is C.
Question 6
[edit | edit source]- What type of antennas are the quad, Yagi, and dish?
- A. Non-resonant antennas
- B. Loop antennas
- C. Directional antennas
- D. Isotropic antennas
The correct answer is C.
Question 7
[edit | edit source]- 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
The correct answer is A.
Question 8
[edit | edit source]- What is the approximate length, in inches, of a quarter-wavelength vertical antenna for 146 MHz?
- A. 112
- B. 50
- C. 19
- D. 12
The correct answer is C.
Question 9
[edit | edit source]- 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
The correct answer is C.
Question 10
[edit | edit source]- 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
The correct answer is C.
Question 11
[edit | edit source]- 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
The correct answer is C.
Question 12
[edit | edit source]- 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
The correct answer is A.
Question 13
[edit | edit source]- 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
The correct answer is C.
Question 14
[edit | edit source]- 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
The correct answer is A.