General exam question G9C11
Subelement G9, ANTENNAS AND FEED LINES· Group G9C
What is a beta or hairpin match?
- A.A shorted transmission line stub placed at the feed point of a Yagi antenna to provide impedance matching (correct answer)
- 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
WhyA beta or hairpin match is a shorted transmission line stub placed at the feed point of a Yagi antenna to provide impedance matching. A beta, or hairpin, match places a shorted transmission-line stub right at a Yagi's feed point, and adjusting that stub's length or position tunes out the reactance mismatch to bring the antenna's impedance into line with the feed line, answer A. It isn't built from a quarter-wave section of 75-ohm coax (that describes a different matching technique), isn't a series capacitor canceling folded-dipole reactance, and isn't a twin-lead matching section for a folded dipole, so B, C, and D describe other matching methods.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2023-2027 NCVEC Element 3 pool (public domain); the explanation above is original writing, see our methodology.
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