General exam question G5C07
Subelement G5, ELECTRICAL PRINCIPLES· Group G5C
What transformer turns ratio matches an antenna’s 600-ohm feed point impedance to a 50-ohm coaxial cable?
- A.3.5 to 1 (correct answer)
- B.12 to 1
- C.24 to 1
- D.144 to 1
WhyA transformer turns ratio of about 3.5 to 1 matches an antenna's 600-ohm feed point impedance to 50-ohm coaxial cable. Matching impedances through a transformer requires a turns ratio equal to the square root of the impedance ratio, so √(600/50), the square root of 12, comes out to about 3.5 to 1, answer A. The larger ratios in B, C, and D would be appropriate for matching much larger impedance differences than 600 ohms to 50 ohms.
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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