Which of the following describes an extended double Zepp antenna?
The correct answer is C: A center-fed 1.25-wavelength dipole antenna. An extended double Zepp antenna is a center-fed 1.25-wavelength dipole antenna. It's longer than a standard half-wave dipole, giving it different characteristics.
The extended double Zepp is essentially a dipole that's 1.25 wavelengths long (2.5 times a half-wave). It's center-fed like a standard dipole but longer. The extra length creates a different current distribution and radiation pattern compared to a half-wave dipole. The name 'extended double Zepp' comes from being an extended version of the double Zepp (which is 1 wavelength). This longer length can provide some gain and different pattern characteristics compared to a standard dipole.
Exam Tip
Extended double Zepp = Center-fed 1.25-wavelength dipole. Remember: An extended double Zepp is a center-fed 1.25-wavelength (2.5 × half-wave) dipole antenna.
Memory Aid
"**E**xtended **D**ouble **Z**epp = **C**enter-**F**ed **1**.**25**λ (think 'EDZ = CF1.25λ')"
Real-World Application
You build an extended double Zepp antenna. You cut a wire 1.25 wavelengths long and feed it at the center. This is longer than a standard half-wave dipole, creating a different current distribution and radiation pattern. The extra length can provide some gain compared to a standard dipole.
FCC Part 97.3Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. An extended double Zepp is center-fed, not end-fed. And it's 1.25 wavelengths, not a full wave.
Option B: Incorrect. An extended double Zepp is 1.25 wavelengths, not 1.5 wavelengths.
Option D: Incorrect. An extended double Zepp is center-fed, not end-fed. And it's 1.25 wavelengths, not 2 wavelengths.
题目解析
The correct answer is C: A center-fed 1.25-wavelength dipole antenna. An extended double Zepp antenna is a center-fed 1.25-wavelength dipole antenna. It's longer than a standard half-wave dipole, giving it different characteristics. The extended double Zepp is essentially a dipole that's 1.25 wavelengths long (2.5 times a half-wave). It's center-fed like a standard dipole but longer. The extra length creates a different current distribution and radiation pattern compared to a half-wave dipole. The name 'extended double Zepp' comes from being an extended version of the double Zepp (which is 1 wavelength). This longer length can provide some gain and different pattern characteristics compared to a standard dipole.
考试技巧
Extended double Zepp = Center-fed 1.25-wavelength dipole. Remember: An extended double Zepp is a center-fed 1.25-wavelength (2.5 × half-wave) dipole antenna.
记忆口诀
**E**xtended **D**ouble **Z**epp = **C**enter-**F**ed **1**.**25**λ (think 'EDZ = CF1.25λ')
实际应用示例
You build an extended double Zepp antenna. You cut a wire 1.25 wavelengths long and feed it at the center. This is longer than a standard half-wave dipole, creating a different current distribution and radiation pattern. The extra length can provide some gain compared to a standard dipole.
错误选项分析
Option A: Incorrect. An extended double Zepp is center-fed, not end-fed. And it's 1.25 wavelengths, not a full wave. Option B: Incorrect. An extended double Zepp is 1.25 wavelengths, not 1.5 wavelengths. Option D: Incorrect. An extended double Zepp is center-fed, not end-fed. And it's 1.25 wavelengths, not 2 wavelengths.
知识点
Extended double Zepp, 1.25-wavelength, Center-fed dipole, Long dipole
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.