Points on the reactance axis have a resistance of 0 ohms. The arcs on a Smith chart represent points with constant reactance, and the large outer circle on which the reactance arcs terminate is called the reactance axis. QUESTION: On the Smith chart shown in Figure E9-3, what is the only straight line shown? (E9G07) ANSWER: The resistance axis QUESTION: What are the two families of circles and arcs that make up a Smith chart? (E9G04) ANSWER: Resistance and reactance QUESTION: What type of coordinate system is used in a Smith chart? (E9G02) ANSWER: Resistance circles and reactance arcs In practice, you want to position the chart so that 0 ohms is at the far left, while infinity is at the far right. Points on this axis are pure resistances. The resistance axis is the only straight line on the Smith chart.
The Smith chart coordinate system is comprised of resistance circles and reactance arcs. While a complete discussion of the theory behind the Smith Chart is outside the scope of this study guide, a good discussion of the Smith Chart can be found on the ARRL website. A Smith chart, shown in Figure E9-3 above, is a chart designed to solve transmission line problems graphically.
