Question
What is a beta or hairpin match?
Answer Options
- A) A shorted transmission line stub placed at the feed point of a Yagi antenna to provide impedance matching
- B) A 1/4 wavelength section of 75-ohm coax in series with the feed point of a Yagi to provide impedance matching
- C) A series capacitor selected to cancel the inductive reactance of a folded dipole antenna
- D) A section of 300-ohm twin-lead transmission line used to match a folded dipole antenna
Correct Answer: A
Explanation
The beta match, often implemented as a hairpin match, is a common technique used to match the low, complex impedance of a driven element (like the center element of a Yagi) to the 50 \text{ ohm} coaxial cable.
The hairpin match consists of a shorted transmission line stub placed at the feed point of a Yagi antenna to provide impedance matching. This parallel stub adds inductive reactance to cancel out the capacitive reactance present at the driven element’s feed point, leaving a purely resistive impedance that is easily matched to the feed line.
This topic was automatically created to facilitate community discussion about this exam question. Feel free to share study tips, memory tricks, or additional explanations!