Question
What is the nominal characteristic impedance of “window line” transmission line?
Answer Options
- A) 50 ohms
- B) 75 ohms
- C) 100 ohms
- D) 450 ohms
Correct Answer: D
Explanation
“Window line” is a type of parallel conductor feed line, often referred to simply as ladder line, characterized by its low-loss construction using plastic or synthetic material separating the two conductors with cut-out windows. This construction is designed to minimize the dielectric material to reduce loss.
Based on its physical spacing and conductor size, the nominal characteristic impedance of window line feed line is typically 450 ohms. This makes it suitable for feeding balanced antennas, especially multi-band antennas whose feed point impedance varies widely.
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