How do the lengths of a three-element Yagi reflector and director compare to that of the driven element?
The correct answer is A: The reflector is longer, and the director is shorter. How the lengths of a three-element Yagi reflector and director compare to that of the driven element is that the reflector is longer, and the director is shorter. Reflector is longer to reflect signals, director is shorter to direct signals forward. For amateur radio operators, this is fundamental Yagi design. Understanding this helps when building Yagi antennas.
Exam Tip
Yagi element lengths = reflector longer, director shorter. Think 'R'eflector = 'R'eflects (longer), 'D'irector = 'D'irects forward (shorter). Reflector is longer to reflect signals, director is shorter to direct signals forward. Not backwards, not same, not frequency-dependent - just reflector longer, director shorter.
Memory Aid
"Yagi element lengths = reflector longer, director shorter. Think 'R'eflector = 'R'eflects (longer), 'D'irector = 'D'irects (shorter). Reflector is longer to reflect signals, director is shorter to direct signals forward. Fundamental Yagi design."
Real-World Application
A three-element Yagi: The reflector is longer than the driven element (to reflect signals backward), and the director is shorter than the driven element (to direct signals forward). This creates the directional pattern. Reflector longer, director shorter - this is fundamental Yagi design.
Key Concepts
Why Other Options Are Wrong
Option B: Incorrect. Reflector shorter and director longer is backwards - reflector should be longer, director shorter. Backwards is wrong.
Option C: Incorrect. They're not all the same length - reflector is longer, director is shorter. Same length is wrong.
Option D: Incorrect. Relative length doesn't depend on frequency - reflector is always longer, director shorter, regardless of frequency. Frequency dependence is wrong.
题目解析
The correct answer is A: The reflector is longer, and the director is shorter. How the lengths of a three-element Yagi reflector and director compare to that of the driven element is that the reflector is longer, and the director is shorter. Reflector is longer to reflect signals, director is shorter to direct signals forward. For amateur radio operators, this is fundamental Yagi design. Understanding this helps when building Yagi antennas.
考试技巧
Yagi element lengths = reflector longer, director shorter. Think 'R'eflector = 'R'eflects (longer), 'D'irector = 'D'irects forward (shorter). Reflector is longer to reflect signals, director is shorter to direct signals forward. Not backwards, not same, not frequency-dependent - just reflector longer, director shorter.
记忆口诀
Yagi element lengths = reflector longer, director shorter. Think 'R'eflector = 'R'eflects (longer), 'D'irector = 'D'irects (shorter). Reflector is longer to reflect signals, director is shorter to direct signals forward. Fundamental Yagi design.
实际应用示例
A three-element Yagi: The reflector is longer than the driven element (to reflect signals backward), and the director is shorter than the driven element (to direct signals forward). This creates the directional pattern. Reflector longer, director shorter - this is fundamental Yagi design.
错误选项分析
Option B: Incorrect. Reflector shorter and director longer is backwards - reflector should be longer, director shorter. Backwards is wrong. Option C: Incorrect. They're not all the same length - reflector is longer, director is shorter. Same length is wrong. Option D: Incorrect. Relative length doesn't depend on frequency - reflector is always longer, director shorter, regardless of frequency. Frequency dependence is wrong.
知识点
Yagi antenna, Reflector, Director, Element lengths
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.