BasicB-006-003-001
A transmission line must be supported for several metres by attaching it to a metal fence. What type of transmission line will NOT be adversely affected by proximity to the fence?
A
Answer
Antennas and feed lines
Type
A
Coaxial cable
B
Open-wire line
C
Twin-lead
D
Window line
Answer Notes
Coaxial cable consists of a center conductor completely surrounded by a metallic shield. Because the electromagnetic field carrying the signal is confined entirely within this outer shield, coaxial cable is not significantly affected by being routed near metallic objects.
In contrast, parallel-conductor lines like open-wire, twin-lead, and window line rely on the space surrounding them to carry their electromagnetic fields. If these balanced lines are placed too close to a metal fence or structure, the metal will interact with the fields, altering the line's impedance and causing it to become unbalanced and radiate energy.
As a result, coaxial cable is the only practical choice when a transmission line must be run alongside or attached directly to metal structures.
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What kind of transmission line has two conductors maintained side by side, a constant distance apart, using insulated spreaders?
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