Sub-Element T9 Antennas & feed lines [2 Exams Questions]

Question 1

What is a beam antenna?

Answer 1

An antenna that concentrates signals in one direction

Question 2

Which of the following describes a type of antenna loading?

Answer 2

Inserting an inductor in the radiating portion of the antenna to make it electrically longer

Question 3

Which of the following describes a simple dipole oriented parallel to the Earth’s surface?

Answer 3

A horizontally polarized antenna

Question 4

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

Answer 4

It does not transmit or receive as effectively

Question 5

How would you change a dipole antenna to make it resonant on a higher frequency?

Answer 5

Shorten it

Question 6

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

Answer 6

Directional antennas

Question 7

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

Answer 7

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

Question 8

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

Answer 8

19

Question 9

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

Answer 9

112

Question 10

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

Answer 10

Broadside to the antenna

Question 11

What is the gain of an antenna?

Answer 11

The increase in signal strength in a specified direction compared to a reference antenna

Question 12

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

Answer 12

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

Question 13

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

Answer 13

To reduce signal loss

Question 14

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

Answer 14

50 ohms

Question 15

Why is coaxial cable the most common feed line selected for amateur radio antenna systems?

Answer 15

It is easy to use and requires few special installation considerations

Question 16

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

Answer 16

It matches the antenna system impedance to the transceiver’s output impedance

Question 17

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

Answer 17

The loss increases

Question 18

Which of the following connectors is most suitable for frequencies above 400 MHz?

Answer 18

A Type N connector

Question 19

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

Answer 19

They are commonly used at HF frequencies

Question 20

Why should coax connectors exposed to the weather be sealed against water intrusion?

Answer 20

To prevent an increase in feed line loss

Question 21

What can cause erratic changes in SWR readings?

Answer 21

A loose connection in an antenna or a feed line

Question 22

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

Answer 22

RG-8 cable has less loss at a given frequency

Question 23

Which of the following types of feed line has the lowest loss at VHF and UHF?

Answer 23

Air-insulated hard line