Stored energy in general antenna system: A new approach

The present paper introduces a new formulation of electromagnetic stored energy based on a simple operational definition of the energy stored in the fields of radiating structures. The new definition is in harmony with the accepted understanding of energy in physics as the latent capacity to perform work. The proposed approach rejects the conventional consideration of reactive energy as stored energy and replaces the later with a procedure through time domain measurements of the sum of both re-radiated field energy and port energy. The paper proposes a new recovery factor that estimates the amount of stored energy available at the port, which is the basic performance measure we anticipate for energy handling and harvesting applications using antenna systems. Examples and numerical experiments are provided to illustrate the theory and in order to provide new insights into the operational characteristics of simple but important practical radiating structures like dipole and loop antennas.