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Subelement B-006

B-006

Section B-006-002

Section B-006-002

What kind of transmission line has a centre wire inside an insulating material that is covered by a metal shield or sleeve?

  • Correct Answer
    Coaxial cable
  • Window line
  • Waveguide
  • Open-wire line

Coaxial: two concentric conductors, an inner conductor, a dielectric (insulator) and an outer conductor (braided or solid). 'Window line' (a type of parallel line) looks like a ribbon. 'Open wire line' or 'ladder line' (a type of parallel line) uses insulating rods. [ 'Twisted pair' is very rarely used in radio work. ]

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

What kind of transmission line has two wires side-by-side embedded in insulating material?

  • Open-wire line
  • Coaxial cable
  • Waveguide
  • Correct Answer
    Window line

"Two wires held apart by insulating rods (spacers or 'spreaders')" is also known as 'open wire line' or 'ladder line'.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

What kind of transmission line is made of two conductors held apart by insulated rods?

  • Window line
  • Correct Answer
    Open-wire line
  • Twisted pair
  • Coaxial cable

"Two wires held apart by insulating rods (spacers or 'spreaders')" is also known as 'open wire line' or 'ladder line'.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

What is the purpose of a balun?

  • Correct Answer
    Connect balanced and unbalanced systems
  • Balance antenna impedance
  • Shunt common-mode current to ground
  • Increase antenna gain

"Balun" is the contraction of "BALanced to UNbalanced". Dipole antennas and parallel lines operate in a BALanced mode (two conductors float above ground potential). A quarter-wave antenna, a ground-plane antenna and coaxial cable operate in an UNbalanced mode (with one side grounded). A BALUN interfaces balanced antenna to unbalanced transmission line OR balanced line to unbalanced line. A BALUN can also include impedance transformation.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

Where would you install a balun to feed a dipole antenna with 50-ohm coaxial cable?

  • Between the transmitter and the coaxial cable
  • Between the antenna and the ground
  • Between the coaxial cable and the ground
  • Correct Answer
    Between the coaxial cable and the antenna

"Balun" is the contraction of "BALanced to UNbalanced". Dipole antennas and parallel lines operate in a BALanced mode (two conductors float above ground potential. A quarter-wave antenna, a ground-plane antenna and coaxial cable operate in an UNbalanced mode (with one side grounded). A BALUN interfaces balanced antenna to unbalanced transmission line OR balanced line to unbalanced line. A BALUN can also include impedance transformation.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

What causes a transmission line to be unbalanced?

  • Correct Answer
    One conductor is connected to ground
  • The conductors are twisted together
  • The conductors have deteriorated insulation
  • One conductor has a poor connection at the antenna

Key word: UNBALANCED. An 'UNbalanced' transmission line functions with one conductor connected to ground (like coaxial cable or 'coax' for short). A 'balanced' transmission line operates with both conductors floating above ground potential (like all types of parallel lines: window line, open-wire line).

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

What device can be installed to feed a balanced antenna with an unbalanced transmission line?

  • Correct Answer
    A balun
  • A loading coil
  • A wave trap
  • A triaxial transformer

"Balun" is the contraction of "BALanced to UNbalanced". Dipole antennas and parallel lines operate in a BALanced mode (two conductors float above ground potential. A quarter-wave antenna, a ground-plane antenna and coaxial cable operate in an UNbalanced mode (with one side grounded). A BALUN interfaces balanced antenna to unbalanced transmission line OR balanced line to unbalanced line. A BALUN can also include impedance transformation.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

What device should you use to connect a coaxial cable to window line?

  • A surge suppressor
  • A phasing harness
  • A tuning stub
  • Correct Answer
    A balun

"Balun" is the contraction of "BALanced to UNbalanced". Dipole antennas and parallel lines operate in a BALanced mode (two conductors float above ground potential). A quarter-wave antenna, a ground-plane antenna and coaxial cable operate in an UNbalanced mode (with one side grounded). A BALUN interfaces balanced antenna to unbalanced transmission line OR balanced line to unbalanced line. A BALUN can also include impedance transformation.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

A balanced transmission line:

  • Correct Answer
    is made of two parallel wires
  • is made of one conductor only
  • has one conductor inside the other
  • carries RF current on one wire only

Key word: BALANCED. A 'balanced' transmission line operates with both conductors floating above ground potential (like all types of parallel lines: window line, open-wire line). An 'UNbalanced' transmission line functions with one conductor connected to ground (like coaxial cable or 'coax' for short).

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

Your antenna tuner does not have a balanced output and you wish to use window line to feed an HF antenna. What device should you use between the tuner and the transmission line?

  • Quarter-wave transformer
  • Correct Answer
    Balun
  • Autotransformer
  • Transmission line stub

"Balun" is the contraction of "BALanced to UNbalanced". Dipole antennas and parallel lines operate in a BALanced mode (two conductors float above ground potential). A quarter-wave antenna, a ground-plane antenna and coaxial cable operate in an UNbalanced mode (with one side grounded). A BALUN interfaces balanced antenna to unbalanced transmission line OR balanced line to unbalanced line. A BALUN can also include impedance transformation.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

What kind of transmission line has two conductors maintained side by side, a constant distance apart, using insulated spreaders?

  • Twisted pair
  • Twin-lead
  • Correct Answer
    Open-wire line
  • Coaxial cable

"Two wires held apart by insulating rods (spacers or 'spreaders')" is also known as 'open wire line' or 'ladder line'. 'Window line' is two conductors held apart in a plastic ribbon. Coaxial cable is two concentric conductors, an inner conductor, a dielectric (insulator) and an outer conductor (braided or solid).

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

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