E9H03:What is receiving directivity factor (RDF)?

Direct answer summary (2024-2028 NCVEC pool)

The official correct answer for E9H03 is Peak antenna gain compared to average gain over the hemisphere around and above the antenna.

The key fact is Peak antenna gain compared to average gain over the hemisphere around and above the antenna. Match that fact to the exact condition in the question; the other choices describe a different rule, band, component, or operating situation.