FREE Ham Radio General Class Test Antennas and Feed Lines Questions and Answers

Question 1

What is the primary purpose of an antenna tuner (transmatch)?

Accepted Answer

To match the impedance of the transceiver to the impedance of the feed line and antenna system.

Answer

To absorb harmonic radiation and prevent its transmission.

Answer

To increase the antenna's gain and directivity.

Answer

To filter out noise and interference before it reaches the receiver.

Question 2

In a Yagi antenna, what is the typical relationship in length between the driven element, the reflector, and the directors?

Accepted Answer

The reflector is the longest, the driven element is shorter, and the directors are the shortest.

Answer

The driven element is the longest, the reflector is shorter, and the directors are the shortest.

Answer

All elements are the same length for maximum resonance.

Answer

The directors are the longest, the driven element is shorter, and the reflector is the shortest.

Question 3

A technician measures the SWR at the transmitter end of a long coaxial feed line and gets a reading of 1.1:1. However, the antenna itself is known to be a poor match for the operating frequency. What is the most likely reason for the low SWR reading?

Accepted Answer

The long feed line is attenuating the reflected wave, making the SWR appear lower than it is at the antenna.

Answer

The SWR meter is malfunctioning.

Answer

The transmitter's output power is too low for an accurate reading.

Answer

The antenna has been correctly matched by the length of the feed line.

Question 4

What is the primary radiation pattern of a simple quarter-wavelength vertical antenna installed with a good ground-plane system?

Accepted Answer

Omnidirectional in the horizontal plane.

Answer

A figure-8 pattern with nulls off the sides.

Answer

Primarily directional, with maximum radiation off the top of the antenna.

Answer

A cardioid pattern with a deep null in one direction.

Question 5

The velocity factor of a coaxial cable is primarily determined by which of its physical properties?

Accepted Answer

The type of dielectric material used between the center conductor and shield.

Answer

The conductivity of the center conductor and shield.

Answer

The overall diameter of the cable.

Answer

The tightness of the outer jacket.

Question 6

An amateur operator is setting up an HF station and finds the SWR is 3:1 on their desired frequency. Which of the following is the most likely consequence of operating with this high SWR?

Accepted Answer

The transceiver may reduce its output power to protect its final amplifier circuits.

Answer

Increased signal clarity and audio fidelity.

Answer

Improved antenna efficiency and greater radiated power.

Answer

The feed line will radiate more effectively than the antenna.