A Study on Received and Re-radiated Power of a Receiving Antenna

For a transmitting antenna, the radiated power is equal to the power consumed at the internal impedance of the transmitter when load impedance is equal to a complex conjugate of the internal impedance. However, the received power for a receiving antenna is not always equal to the re-radiated power, e.g., when the antenna length is more than 0.8 wavelength. This paper explains the reason clearly by analyzing the current distribution of the receiving antenna. We separate the current distribution into the coupling component and the non- coupling component. Then we show that the former contributes to the received power at the load but the later does not contribute to the re-radiated power.