Which of the following factors determine the characteristic impedance of a parallel conductor feed line?
The correct answer is A: The distance between the centers of the conductors and the radius of the conductors. Factors that determine the characteristic impedance of a parallel conductor feed line are the distance between the centers of the conductors and the radius of the conductors. Characteristic impedance depends on geometry (spacing and conductor size), not frequency or length. For amateur radio operators, this is fundamental transmission line theory. Understanding this helps when designing feed lines.
Exam Tip
Parallel conductor impedance = distance between centers and conductor radius. Think 'I'mpedance = 'I'nteraction between 'D'istance and 'R'adius. Characteristic impedance depends on geometry (spacing and conductor size), not frequency or length. Not length, not frequency, not frequency+length - just distance and radius.
Memory Aid
"Parallel conductor impedance = distance between centers and conductor radius. Think 'I'mpedance = 'D'istance and 'R'adius. Characteristic impedance depends on geometry (spacing and conductor size), not frequency or length. Fundamental transmission line property."
Real-World Application
A parallel conductor feed line: The characteristic impedance depends on the distance between the conductor centers and the radius of the conductors. For example, wider spacing or larger conductors changes the impedance. Characteristic impedance is a property of the line geometry, not its length or the signal frequency. This is fundamental transmission line theory.
Key Concepts
Why Other Options Are Wrong
Option B: Incorrect. Length doesn't determine characteristic impedance - impedance is a property of the line geometry, not length. Length affects loss, not impedance.
Option C: Incorrect. Frequency doesn't determine characteristic impedance - impedance is independent of frequency (for lossless lines). Frequency affects loss, not impedance.
Option D: Incorrect. Frequency and length don't determine characteristic impedance - impedance depends on geometry, not frequency or length. Both are wrong.
题目解析
The correct answer is A: The distance between the centers of the conductors and the radius of the conductors. Factors that determine the characteristic impedance of a parallel conductor feed line are the distance between the centers of the conductors and the radius of the conductors. Characteristic impedance depends on geometry (spacing and conductor size), not frequency or length. For amateur radio operators, this is fundamental transmission line theory. Understanding this helps when designing feed lines.
考试技巧
Parallel conductor impedance = distance between centers and conductor radius. Think 'I'mpedance = 'I'nteraction between 'D'istance and 'R'adius. Characteristic impedance depends on geometry (spacing and conductor size), not frequency or length. Not length, not frequency, not frequency+length - just distance and radius.
记忆口诀
Parallel conductor impedance = distance between centers and conductor radius. Think 'I'mpedance = 'D'istance and 'R'adius. Characteristic impedance depends on geometry (spacing and conductor size), not frequency or length. Fundamental transmission line property.
实际应用示例
A parallel conductor feed line: The characteristic impedance depends on the distance between the conductor centers and the radius of the conductors. For example, wider spacing or larger conductors changes the impedance. Characteristic impedance is a property of the line geometry, not its length or the signal frequency. This is fundamental transmission line theory.
错误选项分析
Option B: Incorrect. Length doesn't determine characteristic impedance - impedance is a property of the line geometry, not length. Length affects loss, not impedance. Option C: Incorrect. Frequency doesn't determine characteristic impedance - impedance is independent of frequency (for lossless lines). Frequency affects loss, not impedance. Option D: Incorrect. Frequency and length don't determine characteristic impedance - impedance depends on geometry, not frequency or length. Both are wrong.
知识点
Characteristic impedance, Parallel conductor feed line, Distance between conductors, Conductor radius
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.