On the equation determining current distribution for spherical-type helix antennas

Electrically small antennas (ESAs) have been analyzed by both analytical and numerical techniques since ESAs play a significant role in modern communication equipment.For instance, a spherical helix antenna (SHA) is regarded as a theoretical model of a typical resonant ESA.SHA can closely reach a theoretical lower limit on the Q factor and radiation efficiency through the radiation of the lowest TM/TE spherical wave [1].This result is verified by both using numerical simulations and experiments [2].As indicated in the preceding research on analytical modelling of this antenna [2], the analytical treatment is predicated on the assumption of a sinusoidal distribution of a current along the thin wire.