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57 Cards in this Set

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What connecting link is used to transfer energy from a radio transmitter to its antenna located on the mast of a ship?
Transmission Line
What terms are used for the end of the transmission line that is connected to a transmitter? (5)
a) input end
b) generator end
c) transmitter end
d) sending end
e) source
What terms are used for the end of the transmission line that is connected to an antenna? (4)
a) output end
b) receiving end
c) load end
d) sink
Name the five types of transmission lines in use today.
1) parallel two-wire
2) twisted pair
3) shielded pair
4) coaxial line
5) waveguide
Name the three main uses of a two-wire open line.
Power lines
Rural telephone lines
Telegraph lines
What are the two primary disadvantages of a two-wire open line?
High Radiation Losses
Noise Pickup
What type of transmission line is often used to connect a television set to its antenna?
Twin lead
What is the primary advantage of the shielded pair?
The conductors are balanced to ground
What are the two types of coaxial lines in use today?
Air Coaxial (rigid)

Solid Coaxial (flexible)
What is the chief advantage of the air coaxial line?
The ability to minimize radiation losses
List the three disadvantages of the air coaxial line.
a) Epensive to construct
b) Must be kept dry
c) High frequency losses limit the practical length of the line
List the two common types of waveguides in use today.
Cylindrical

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

Dielectric

Radiation
Losses caused by skin effect and the I2(sqrd)R (power) loss are classified as what type of loss?
Copper losses
What types of losses cause the dielectric material between the conductors to be heated?
Dielectric losses
What must the physical length of a transmission line be if it will be operated 15,000 Hz?
Use the formula λ=V/f
λ=20 meters
List three physical factors that determine the values of capacitance and inductance of a transmission line?
(1) Type of line used
(2) Dielectric in the line
(3) Length of line
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?
Inductance- in microhenrys per unit length

Capacitance- in picofarads per unit length,

Resistance- in ohms per unit length
Describe the leakage current in a transmission line and in what unit it is expressed.
Leakage Current: the small amount of current that flows through the dielectric between two wires of a transmission line.

Expressed in= Microhms per unit length
All the power sent down a transmission line from a transmitter can be transferred to an antenna under what optimum conditions?
When the characteristic impedance of the transmission line and the load impedance are equal.
What symbol is used to designate the characteristic impedance of a line, and what two variables does it compare?
Z₀
and it is the ratio of E to I at every point along the line
What is the range of the characteristic impedance of lines used in actual practice?
Between 50 and 600 ohms
Two types of waves are formed on a transmission line. What names are given to these waves and how do they flow?
INCIDENT WAVES from generator to load.

REFLECTED WAVES from load back to generator.
On an open-ended transmission line, the voltage is always zero at what distance from each end of the line?
One-fourth the distance from each end of the line
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?
The load impedance of such a line is equal to Z₀
On an open line, the voltage and impedance are maximum at what points on the line?
Even quarter-wave points (1/2λ, λ, 3/2λ, etc.)
At what point on an open-circuited rf line do voltage peaks occur?
At 1/2 wavelength from the end and at every 1/2 wavelength along the line.
What is the square of the voltage standing-wave ratio called?
Power standing-wave ratio (pswr)
What does vswr measure?
The existance of voltage variations on a line
_______ _______ are devices for guiding electical energy from one point to another.
Transmission Lines
_______ _______ is the ratio of voltage to current at the input end of a transmission line.
Input Impedance
What type of parallel line is used for power lines, rural telephone lines, and telegraph lines?
Two-Wire Open Lines
What type of line is normally used to connect televisions to their antennas?
Twin Lead
What type of line consists of two insulated wires twisted together?
Twisted Pair
What type of line has parallel conductors seperated by a solid dielectric and surrounded by copper braided tubing?
Shielded Pair
What type of line has high radiation losses and is subject to noise pickup?
Two-Wire Open Lines
What type of line has conductors that are balanced to ground?
Shielded Pair
What type of line has high insulation loss?
Twisted Pair
What type of line contains two concentric conducors insulated from each other by spacers?
Rigid Coaxial Line
What type of line consists of a flexible inner conductor and a concentric outer conductor of metal braid which are seperated by a continuous insulating material?
Flexible Coaxial Lines
_______ are hollow metal tubes used to transfer energy from one point to another?
Waveguides
What type of line is pressurized with an inert gas to prevent moisture from entering?
Rigid Coaxial Line
What type of losses can result from (IxIxR) loss, in the form of heat, or skin effect?
Copper Losses
What type of line has the lowest amount of high frequency losses?
Rigid Coaxial Line
What type of loss decreases the conductivity of a line?
Copper Loss
Does the energy in waveguides travel FASTER or SLOWER than in free space?
Slower
Dielectric Losses are caused by......
The heating of the dielectric material between conductors.
Radiation and Induction Losses are caused by......
Part of the electromagnetic fields of a conductor being dissipated into SPACE or NEARBY OBJECTS.
What kind of loss takes power away from the source?
Dielectric Losses
A transmission line is either electrically LONG or SHORT if its physical length is not equal to ____λ
1/4λ
Theoretical properties (inductance, resistance, capacitance) of a transmission line that are combined into a single component are known as _______ _______.
Lumped Constants
Constants of inductance, resistance, and capacitance that are spread along the transmission line are known as _______ _______.
Distributed Constants
Where does LEAKAGE CURRENT flow?
Between the wires of a transmission line through the dielectric.
In Leakage Current, what type of component does the dielectric act as?
A capacitor, inductor, resistor, or transistor?
Resistor
What type of FIELD exists along a transmission line when current flows through it?
Electromagnetic
For maximum transfer, the CHARACTERISTIC IMPEDANCE and the _______ IMPEDANCE must be matched.
Load
A transmission line that is not terminated in its characteristic impedance is said to be _______.
Finite