Total antenna efficiency takes into account the reflection, conduction and dielectric losses of an antenna. The dielectric and conduction losses are difficult to compute and in most cases are measured. Even with measurements, they are difficult to separate and are usually lumped together to form the radiation efficiency (ecd). The radiation efficiency is defined as the ratio of the power delivered to the radiation resistance (Rr) to the power delivered to the radiation resistance and the conduction-dielectric resistance (RL), or in equation form as displayed above.
ecd = antenna radiation efficiency
Rr = radiation resistance
RL = resistance representing the combination of the conduction-dielectric losses.