Recoverable Energy of Radiating Structures

In this paper, the maximum “recoverable” energy of a radiator is determined. This energy is defined as the maximum energy that can be recovered from the electromagnetic field distribution in entire space generated by the radiator up to the time point considered. The calculation procedure is based on minimizing the future radiated energy. It is shown that the concept of recoverable energy has no problems with so-called “negative energies,” or with any dependence on coordinate system, issues that compromise many definitions found in literature of the concept of “stored” energy for a radiator. The question can be raised whether “recoverable” energy can be identified with stored energy for a radiator.