Absorption efficiency and physical bounds on antennas

In English The all spectrum absorption efficiency appears in the physical bounds on antennas expressed in the polarizability dyadics. Here, it is shown that this generalized absorption efficiency is close to $1/2$ for small idealized dipole antennas and for antennas with a dominant resonance in their absorption. Also, the usefulness of this parameter is analyzed for estimation of antenna performance. The results are illustrated with numerical data for several antennas.