Forward gain compared to the gain in the reverse direction
Relative directivity compared to isotropic
Relative directivity compared to a dipole
Peak antenna gain compared to average gain over the hemisphere around and above the antenna✓الإجابة الصحيحة
الشرح
Receiving directivity factor compares an antenna's peak gain with its average gain over the entire hemisphere around and above it. Since noise arrives from all of those directions, RDF predicts the signal-to-noise improvement a receiving antenna gives better than forward gain or front-to-back ratio do.