Radiation resistance

Radiation resistance is that part of an antenna's feedpoint resistance that is caused by the radiation of electromagnetic waves from the antenna, as opposed to loss resistance (also called ohmic resistance) which is caused by ordinary electrical resistance in the antenna, or energy lost to nearby objects, such as the earth, which dissipate RF energy as heat. Radiation resistance is that part of an antenna's feedpoint resistance that is caused by the radiation of electromagnetic waves from the antenna, as opposed to loss resistance (also called ohmic resistance) which is caused by ordinary electrical resistance in the antenna, or energy lost to nearby objects, such as the earth, which dissipate RF energy as heat. The energy depleted by loss resistance is converted to heat radiation; the energy lost by radiation resistance is converted to radio waves. When the feedpoint is at a voltage minimum, the total of radiation resistance and loss resistance is the electrical resistance of the antenna. The ratio of the radiation resistance to the total resistance is the antenna efficiency.