NAVEDTRA 14182A Module 10 Chapter 3

Question 1

What connecting link is used to transfer energy from a radio transmitter to its
antenna located on the mast of a ship?

Answer 1

Transmission line

Question 2

What term is used for the end of the transmission line that is connected to a
transmitter?

Answer 2

Input end, generator end, transmitter end, sending end, and source

Question 3

What term is used for the end of the transmission line that is connected to an
antenna?

Answer 3

Output end, receiving end, load end and sink

Question 4

List the five types of transmission lines in use today

Answer 4

Parallel two-wire, twisted pair, shielded pair, coaxial line and waveguide.

Question 5

Name two of the three described uses of a two-wire open line

Answer 5

Power lines, rural telephone lines, and telegraph lines.

Question 6

What are the two primary disadvantages of a two-wire open line?

Answer 6

High radiation losses and noise pickup.

Question 7

What type of transmission line is often used to connect a television set to its antenna?

Answer 7

Twin lead

Question 8

What is the primary advantage of the shielded pair?

Answer 8

The conductors are balanced to ground.

Question 9

What are the two types of coaxial lines in use today?

Answer 9

Air coaxial (rigid) and solid coaxial (flexible).

Question 10

What is the chief advantage of the air coaxial line?

Answer 10

The ability to minimize radiation losses

Question 11

List the three disadvantages of the air coaxial line.

Answer 11

Expensive to construct, must be kept dry, and high frequency losses limit the
practical length of the line.

Question 12

List the two common types of waveguides in use today

Answer 12

Cylindrical and rectangular.

Question 13

What are the three types of line losses associated with transmission lines?

Answer 13

Copper, dielectric, and radiation

Question 14

Losses caused by skin effect and the I 2
R (power) loss are classified as what type of
loss?

Answer 14

Copper losses

Question 15

What types of losses cause the dielectric material between the conductors to be
heated?

Answer 15

Dielectric losses.

Question 16

What are two of the three physical factors that determine the values of capacitance
and inductance of a transmission line?

Answer 16

(1) Type of line used, (2) dielectric in the line, and (3) length of line

Question 17

A transmission line is said to have distributed constants of inductance, capacitance,
and resistance along the line. What units of measurement are used to express these
constants?

Answer 17

Inductance is expressed in microhenrys per unit length, capacitance is expressed
in picofarads per unit length, and resistance is expressed in ohms per unit length

Question 18

Describe the leakage current in a transmission line and in what unit it is expressed

Answer 18

The small amount of current that flows through the dielectric between two wires
of a transmission line and is expressed in micromhos per unit length

Question 19

ll the power sent down a transmission line from a transmitter can be transferred to
an antenna under what optimum conditions?

Answer 19

When the characteristic impedance of the transmission line and the load
impedance are equal.

Question 20

What symbol is used to designate the characteristic impedance of a line, and what
two variables does it compare?

Answer 20

Z0 and it is the ratio of E to I at every point along the line.

Question 21

What is the range of the characteristic impedance of lines used in actual practice?

Answer 21

Between 50 and 600 ohms

Question 22

Two types of waves are formed on a transmission line. What names are given to
these waves?

Answer 22

Incident waves from generator to load. Reflected waves from load back to
generator

Question 23

On an open-ended transmission line, the voltage is always zero at what distance
from each end of the line?

Answer 23

One-fourth the distance from each end of the line

Question 24

A nonresonant line is a line that has no standing waves of current and voltage on it
and is considered to be flat. Why is this true?

Answer 24

The load impedance of such a line is equal to Z0.

Question 25

On an open line, the voltage and impedance are maximum at what points on the
line?

Answer 25

Even quarter-wave points (1/2

Question 26

At what point on an open-circuited rf line do voltage peaks occur?

Answer 26

At 1/2 wavelength from the end and at every 1/2 wavelength along the line

Question 27

What is the square of the voltage standing-wave ratio called?

Answer 27

Power standing-wave ratio (pswr)

Question 28

What does vswr measure?

Answer 28

The existence of voltage variations on a line.