  In the context of electromagnetic absorption, it is obvious that for an
infinite planar periodic structure illuminated by a plane wave, the maximum
attainable absorptance, i.e., perfect absorption, is theoretically limited to
100% of the incident power. Here we show that an intriguing possibility of
overcoming this limit arises in finite-size resonant absorbing arrays. We
present a comprehensive analysis of a simple two-dimensional strip array over
an infinite perfectly conducting plane, where the strips are loaded by
reconfigurable impedance loads. The absorptance is defined as the ratio of the
dissipated power per unit length of the strips to the incident power on the
unit length of the array width. The results show that even regular arrays of
impedance strips can slightly overcome the limit of 100% absorptance, while
using aperiodic arrays with optimized loads, absorptance can be significantly
increased as compared with the scenario where the strips are identical. In
principle, by tuning the reconfigurable loads, high super-unity absorptance can
be realized for all angles of illumination.
