Question
What third family of circles is often added to a Smith chart during the process of designing impedance matching networks?
Answer Options
- A) Constant-SWR circles
- B) Transmission line length circles
- C) Coaxial-length circles
- D) Radiation-pattern circles
Correct Answer: A
Explanation
While the core of the Smith Chart is built from constant resistance circles and constant reactance arcs, a third set of circles is often overlaid on the chart to simplify the visualization of mismatch loss and the stability of the impedance as a function of frequency.
This third family of circles is the Constant-SWR circles. These are circles centered exactly on the chart’s center point (the 1.0 normalized impedance point). Every point on a single SWR circle represents an impedance that results in the exact same Standing Wave Ratio. Plotting an impedance and drawing its SWR circle quickly reveals the range of impedances found along the feed line.
An example of a constant-SWR circle, or simply “SWR circle,” is at Smith chart - Wikipedia :
This topic was automatically created to facilitate community discussion about this exam question. Feel free to share study tips, memory tricks, or additional explanations!