However loss <answer>resistance</answer> will generally affect the feedpoint impedance, adding to its resistive (real) component. That <answer>resistance</answer> will consist of the sum of the radiation <answer>resistance</answer> Rr and the loss <answer>resistance</answer> Rloss. If an rms current I is delivered to the terminals of an antenna, then a power of I2Rr will be radiated and a power of I2Rloss will be lost as heat. Therefore, the efficiency of an antenna is equal to Rr / (Rr + Rloss). Of course only the total <answer>resistance</answer> Rr + Rloss can be directly measured.
The addition of Rr and Rloss equals what?
resistance