What is the approximate length of the driven element of a Yagi antenna?
The correct answer is B: 1/2 wavelength. The approximate length of the driven element of a Yagi antenna is 1/2 wavelength. The driven element is typically about 1/2 wavelength, slightly shorter than resonant due to element interactions. For amateur radio operators, this is fundamental Yagi design. Understanding this helps when building Yagi antennas.
Exam Tip
Yagi driven element length = 1/2 wavelength. Think 'D'riven 'E'lement = 'D'ipole 'E'lement = '1'/2 wavelength. Driven element is typically about 1/2 wavelength, slightly shorter than resonant. Not 1/4, not 3/4, not 1 wavelength - just 1/2 wavelength.
Memory Aid
"Yagi driven element length = 1/2 wavelength. Think 'D'riven 'E'lement = 'D'ipole 'E'lement. Driven element is typically about 1/2 wavelength, slightly shorter than resonant. Fundamental Yagi design."
Real-World Application
A Yagi antenna: The driven element is approximately 1/2 wavelength long (slightly shorter than resonant due to element interactions). It's similar to a dipole - the driven element is the active element that's fed. This is fundamental Yagi design - driven element is about 1/2 wavelength.
Key Concepts
Why Other Options Are Wrong
Option A (1/4 wavelength): Incorrect. 1/4 wavelength is too short - driven element is about 1/2 wavelength. 1/4 wavelength is wrong.
Option C (3/4 wavelength): Incorrect. 3/4 wavelength is too long - driven element is about 1/2 wavelength. 3/4 wavelength is wrong.
Option D (1 wavelength): Incorrect. 1 wavelength is too long - driven element is about 1/2 wavelength. 1 wavelength is wrong.
题目解析
The correct answer is B: 1/2 wavelength. The approximate length of the driven element of a Yagi antenna is 1/2 wavelength. The driven element is typically about 1/2 wavelength, slightly shorter than resonant due to element interactions. For amateur radio operators, this is fundamental Yagi design. Understanding this helps when building Yagi antennas.
考试技巧
Yagi driven element length = 1/2 wavelength. Think 'D'riven 'E'lement = 'D'ipole 'E'lement = '1'/2 wavelength. Driven element is typically about 1/2 wavelength, slightly shorter than resonant. Not 1/4, not 3/4, not 1 wavelength - just 1/2 wavelength.
记忆口诀
Yagi driven element length = 1/2 wavelength. Think 'D'riven 'E'lement = 'D'ipole 'E'lement. Driven element is typically about 1/2 wavelength, slightly shorter than resonant. Fundamental Yagi design.
实际应用示例
A Yagi antenna: The driven element is approximately 1/2 wavelength long (slightly shorter than resonant due to element interactions). It's similar to a dipole - the driven element is the active element that's fed. This is fundamental Yagi design - driven element is about 1/2 wavelength.
错误选项分析
Option A (1/4 wavelength): Incorrect. 1/4 wavelength is too short - driven element is about 1/2 wavelength. 1/4 wavelength is wrong. Option C (3/4 wavelength): Incorrect. 3/4 wavelength is too long - driven element is about 1/2 wavelength. 3/4 wavelength is wrong. Option D (1 wavelength): Incorrect. 1 wavelength is too long - driven element is about 1/2 wavelength. 1 wavelength is wrong.
知识点
Yagi antenna, Driven element, 1/2 wavelength, Element length
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.