T9A11:What is antenna gain?

Direct answer summary (2026-2030 NCVEC pool)

The official correct answer for T9A11 is The increase in signal strength in a specified direction compared to a reference antenna.

The key fact is The increase in signal strength in a specified direction compared to a reference antenna. Match that fact to the exact condition in the question; the other choices describe a different rule, band, component, or operating situation.