What is the principle of a Method of Moments analysis?
The correct answer is A: A wire is modeled as a series of segments, each having a uniform value of current. The principle of Method of Moments analysis is that a wire is modeled as a series of segments, each having a uniform value of current. The antenna is divided into small segments, and the current on each segment is calculated.
In Method of Moments, the antenna wire is divided into many short segments. Each segment is assumed to have a uniform current distribution (constant current along that segment). The method then solves for the current value on each segment by applying electromagnetic boundary conditions. This piecewise approach allows complex antennas to be modeled accurately. More segments generally mean more accurate results, but also more computation. The uniform current assumption on each segment is a key simplification that makes the method computationally tractable.
Exam Tip
Method of Moments principle = Segments with uniform current. Remember: Method of Moments models a wire as a series of segments, each with uniform current. The method solves for the current on each segment.
Memory Aid
"**M**ethod of **M**oments = **S**egments **U**niform **C**urrent (think 'MoM = SUC')"
Real-World Application
You're modeling a dipole antenna using Method of Moments. The software divides your dipole into, say, 20 segments. Each segment is assumed to have uniform current (constant along that segment). The method calculates the current value on each segment by solving the electromagnetic equations. This gives you the current distribution along the antenna, which determines the radiation pattern and impedance.
FCC Part 97.3Key Concepts
Why Other Options Are Wrong
Option B: Incorrect. A wire isn't modeled as a single sine-wave current generator. Method of Moments uses multiple segments, each with uniform current, not a single generator.
Option C: Incorrect. Method of Moments models current, not voltage sources. Each segment has uniform current, not voltage.
Option D: Incorrect. Method of Moments models uniform current on segments, not distinct voltage values. The method solves for current distribution, not voltage distribution.
题目解析
The correct answer is A: A wire is modeled as a series of segments, each having a uniform value of current. The principle of Method of Moments analysis is that a wire is modeled as a series of segments, each having a uniform value of current. The antenna is divided into small segments, and the current on each segment is calculated. In Method of Moments, the antenna wire is divided into many short segments. Each segment is assumed to have a uniform current distribution (constant current along that segment). The method then solves for the current value on each segment by applying electromagnetic boundary conditions. This piecewise approach allows complex antennas to be modeled accurately. More segments generally mean more accurate results, but also more computation. The uniform current assumption on each segment is a key simplification that makes the method computationally tractable.
考试技巧
Method of Moments principle = Segments with uniform current. Remember: Method of Moments models a wire as a series of segments, each with uniform current. The method solves for the current on each segment.
记忆口诀
**M**ethod of **M**oments = **S**egments **U**niform **C**urrent (think 'MoM = SUC')
实际应用示例
You're modeling a dipole antenna using Method of Moments. The software divides your dipole into, say, 20 segments. Each segment is assumed to have uniform current (constant along that segment). The method calculates the current value on each segment by solving the electromagnetic equations. This gives you the current distribution along the antenna, which determines the radiation pattern and impedance.
错误选项分析
Option B: Incorrect. A wire isn't modeled as a single sine-wave current generator. Method of Moments uses multiple segments, each with uniform current, not a single generator. Option C: Incorrect. Method of Moments models current, not voltage sources. Each segment has uniform current, not voltage. Option D: Incorrect. Method of Moments models uniform current on segments, not distinct voltage values. The method solves for current distribution, not voltage distribution.
知识点
Method of Moments, Wire segments, Uniform current, Antenna modeling
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.