What are the two families of circles and arcs that make up a Smith chart?
The correct answer is C: Resistance and reactance. The two families of circles and arcs that make up a Smith chart are resistance and reactance. Resistance is represented by circles, and reactance is represented by arcs.
The Smith chart consists of two families of curves: circles of constant resistance and arcs of constant reactance. Resistance circles are horizontal circles centered on the horizontal axis. Reactance arcs are curved lines - inductive reactance in the upper half, capacitive reactance in the lower half. Together, these two families create a grid where any impedance (R + jX) can be plotted. The intersection of a resistance circle and a reactance arc gives you a specific impedance point. This is the fundamental structure of the Smith chart.
Exam Tip
Smith chart families = Resistance and reactance. Remember: The two families making up a Smith chart are resistance (circles) and reactance (arcs). Together they represent all possible impedances.
Memory Aid
"**S**mith **C**hart **F**amilies = **R**esistance + **R**eactance (think 'SCF = R+R')"
Real-World Application
You look at a Smith chart. You see circles representing constant resistance (maybe 0, 25, 50, 100, infinity ohms) and arcs representing constant reactance (maybe -j100, -j50, 0, +j50, +j100 ohms). These two families of curves create the grid where you plot impedances.
FCC Part 97.3Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Inductance and capacitance aren't the two families. The chart uses resistance and reactance, which can represent inductive or capacitive components.
Option B: Incorrect. Reactance and voltage aren't the two families. The chart uses resistance and reactance.
Option D: Incorrect. Voltage and impedance aren't the two families. The chart uses resistance and reactance as the coordinate system.
题目解析
The correct answer is C: Resistance and reactance. The two families of circles and arcs that make up a Smith chart are resistance and reactance. Resistance is represented by circles, and reactance is represented by arcs. The Smith chart consists of two families of curves: circles of constant resistance and arcs of constant reactance. Resistance circles are horizontal circles centered on the horizontal axis. Reactance arcs are curved lines - inductive reactance in the upper half, capacitive reactance in the lower half. Together, these two families create a grid where any impedance (R + jX) can be plotted. The intersection of a resistance circle and a reactance arc gives you a specific impedance point. This is the fundamental structure of the Smith chart.
考试技巧
Smith chart families = Resistance and reactance. Remember: The two families making up a Smith chart are resistance (circles) and reactance (arcs). Together they represent all possible impedances.
记忆口诀
**S**mith **C**hart **F**amilies = **R**esistance + **R**eactance (think 'SCF = R+R')
实际应用示例
You look at a Smith chart. You see circles representing constant resistance (maybe 0, 25, 50, 100, infinity ohms) and arcs representing constant reactance (maybe -j100, -j50, 0, +j50, +j100 ohms). These two families of curves create the grid where you plot impedances.
错误选项分析
Option A: Incorrect. Inductance and capacitance aren't the two families. The chart uses resistance and reactance, which can represent inductive or capacitive components. Option B: Incorrect. Reactance and voltage aren't the two families. The chart uses resistance and reactance. Option D: Incorrect. Voltage and impedance aren't the two families. The chart uses resistance and reactance as the coordinate system.
知识点
Smith chart, Resistance, Reactance, Circles and arcs
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.