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

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.