Calculation of stored electromagnetic powers and Q factors of very small normal-mode helical antennas

Theoretical explanations of radiated, dissipated and stored energies of small antennas were shown in a textbook. However, practical values of these energies were not discussed previously. In this paper, these energies are obtained numerically through electromagnetic simulations. As for a study object, a normal-mode helical antenna is utilized, because stored electric and magnetic energies are simultaneously observed. First of all, it is shown that these two energies have the same value at the self-resonant conditions. Next, electric and magnetic stored powers are calculated from these energies and are compared with the input power. Moreover, antenna Q factors are also obtained. Adequateness of calculated results is ensured thorough comparing with other calculated results. © 2013 IEEE.