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20 Cards in this Set
- Front
- Back
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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.
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What term is used for the end of the transmission line that is connected to a transmitter?
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Input end, generator end, transmitter end, sending end, and source
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What term is used for the end of the transmission line that is connected to an antenna?
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Output end, receiving end, load end and sink.
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List the five types of transmission lines in use today.
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Parallel two-wire, twisted pair, shielded pair, coaxial line and waveguide.
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Name two of the three described uses of a two-wire open line
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Power lines, rural telephone lines, and telegraph lines
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What are the two primary disadvantages of a two-wire open line?
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High radiation losses and noise pickup
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What type of transmission line is often used to connect a television set to its antenna?
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Twin lead.
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What is the primary advantage of the shielded pair?
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The conductors are balanced to ground.
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What are the two types of coaxial lines in use today?
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Air coaxial (rigid) and solid coaxial (flexible).
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What is the chief advantage of the air coaxial line?
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The ability to minimize radiation losses
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List the three disadvantages of the air coaxial line.
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Expensive to construct, must be kept dry, and high frequency losses limit the practical length of
the line |
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List the two common types of waveguides in use today.
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Cylindrical and rectangular.
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What are the three types of line losses associated with transmission lines?
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Copper, dielectric, and radiation
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Losses caused by skin effect and the I 2 R (power) loss are classified as what type of loss?
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Copper losses
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What types of losses cause the dielectric material between the conductors to be heated?
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Dielectric losses.
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What must the physical length of a transmission line be if it will be operated at 15,000,000 Hz?
Use the formula: |
20meters
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What are two of the 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, and (3) length of line.
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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 is expressed in microhenrys per unit length, capacitance is expressed in picofarads per
unit length, and resistance is expressed in ohms per unit length |
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Describe the leakage current in a transmission line and in what unit it is expressed.
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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. |
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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.
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