Insights From the Radiation and Energy Storage Modes of Canonical Dipole Antennas

Decomposing the method of moments (MoM) impedance matrix of an antenna into its constituent eigenmodes can provide valuable insight into its behavior. Here, we analyze the radiation and energy storage modal solutions of canonical dipole antennas to establish an intuitive correspondence between an antenna's mode of operation and its modal solutions. Examining these solutions as a function of frequency reveals clear modal transitions that directly affect radiation behavior. Specifically, we demonstrate that the radiation modes are well suited to identify and quantify changes in radiation behavior, because their solutions are decoupled from the energy storage properties of an antenna. We achieve this through the presentation of several examples, which include the analysis of modal changes that occur when an antenna is electrically small versus electrically resonant, as well as when the geometry of an antenna is parametrically modified.