On matching lossy antennas for maximum power absorption

The impedance matching required for maximum absorption by a stand-alone lossy dipole and by an infinite array of lossy dipoles located in front of a ground plane is analyzed. In the case of the stand-alone terminal-loaded lossy dipole, we find an approximate analytical expression for the load impedance that maximizes the sum of the powers absorbed by the load and by the lossy material of which the dipole is made. Evidently, this load is different from the conjugate-matched load, which is required to maximize the load power alone. In the case of the infinite array of terminal-loaded lossy dipoles above a ground plane, we show that if the antennas are terminated with the proper load impedance, one can attain perfect absorption even when the array lies very close to the ground plane. In this case, we also identify the minimum height below which perfect absorption cannot be realized and the absorption efficiency rapidly drops.