Three-dimensional omni-directional power pattern using rotating electric current sphere via exact maxwell solution

Abstract

The author reveals that the power pattern for a particular selected rotating spherical electric current density profile exhibits the following two properties simultaneously: (a) fully omnidirectional in three dimensions (3-D) and (b) invariant with regards to radio frequency (RF). Specifically, most known antenna designs exhibit either nodal lines or planes for at least some RF frequencies. In contrast, the primary innovation of the subject rotating electric current sphere is that it generates a power pattern that is characterised by no nodal lines nor nodal planes for any RF frequency. In the present analysis, the electro-magnetic (EM) fields are calculated as an exact solution of Maxwell's equations for the subject electric current density that rotates azimuthally on a spherical surface. As expected, the spatial structure of the resulting EM fields also rotates azimuthally. More surprisingly, this rotating electric current density generates pure magnetic dipole radiation exactly, with the absence of any higher order multipole moments. This proposed antenna concept could offer utility in various applications, including communications beaconing and radar surveillance.