Electrically small magnetic dipole antennas with magnetic core

This work extends the theory of a spherical magnetic dipole antenna with magnetic core by numerical results for practical antenna configurations that excite higher-order modes besides the main TE₁₀ spherical mode. The multiarm spherical helix (MSH) and the spherical split ring (SSR) antennas are considered. It is shown that one should be particularly aware of the TM₁₁ and TM₂₀ modes, whose resonances spoil the Q in a range of permeability of the core predicted to be optimal by the single-mode theory. Practical ways of suppressing these higher-order modes are presented.