What is the term used for an equivalent resistance which would dissipate the same amount of energy as that radiated from an antenna?

Radiation resistance is a theoretical concept used to model how much power an antenna radiates into space. It is defined as the value of an equivalent resistor that would dissipate the exact same amount of power as the antenna actually radiates as electromagnetic waves. When calculating antenna efficiency, this useful radiated power is compared against the power lost as heat, which is called ohmic resistance. Distractors like "antenna resistance" are too generic, usually referring to the total feedpoint resistance (which includes both radiation and ohmic resistance), while "j factor" relates to complex reactance rather than dissipated power.