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

Question 1

 * 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

 * 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

 * 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

 * 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

 * 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

 * 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

 * 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

 * 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

 * 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

 * 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

 * 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

 * 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

 * 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

 * 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.