Modal Current Distribution for Electrically Small Spherical Helix Antenna

An electrically small spherical helix antenna (SHA) has been developed to achieve high performance communication devices. A wire on a spherical surface can achieve high radiation efficiency and low Q factor compared to conventional normal mode helix antenna. Spherical region inside the wire effectively contributes to the radiated power. A radiation mechanism of such high performance is explained by theoretical model in terms of the vector spherical harmonics. A combination of TE + TM lowest modes form the theoretical model and can illustrate a radiation pattern of the SHA.