Extra exam question E4B03
Subelement E4, AMATEUR PRACTICES· Group E4B
E4B03
Which S parameter is equivalent to forward gain?
- A.S11
- B.S12
- C.S21 (correct answer)
- D.S22
WhyS21 is the S parameter equivalent to forward gain. In two-port S-parameter notation, S21 describes the signal coming out of port 2 relative to what went into port 1, which is exactly the definition of forward gain through the device, answer C. S11 and S22 are input and output return loss respectively, and S12 is reverse gain, the signal leaking backward from port 2 to port 1, none of which is forward gain.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2024-2028 NCVEC Element 4 pool (public domain); the explanation above is original writing, see our methodology.
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