Purcell-Like Environmental Enhancement of Classical Antennas: Self and Transfer Effects

Environmental 'range boosts' in wireless links are often explained through radiation-pattern intuition, yet the underlying physics is more cleanly captured by two environment-controlled quantities: radiative damping of the radiator and \emph{channel coupling} between transmitter and receiver. Building from a dyadic-Green-function current--field formulation, we introduce an operational two-factor description of Purcell-like behavior for classical antennas. A \emph{self} factor quantifies environment-induced changes in radiative damping under an explicit excitation convention, while a \emph{transfer} factor quantifies environment-induced changes in Tx--Rx coupling. We provide measurement-aware extraction workflows (VNA $S_{11}\!\rightarrow Z_{\mathrm{in}}$ with efficiency and realized-gain accounting; link-test normalization to isolate $F_{\mathrm{tr}}$) and falsification diagnostics that prevent conflating true radiative enhancement with mismatch or added absorption. Finally, we translate self/transfer modifications into link-budget and range scalings and illustrate the framework across practical environments from VHF to mmWave, including platforms/ground planes, body proximity, field-expedient environmental radiators, terrain and passive redirection, tunnel/canyon confinement, and engineered scattering environments such as reflectarrays, metasurfaces, and reconfigurable intelligent surfaces (RIS).