Angular Momentum of Rotating Dipole

Abstract

In this paper, we derive the far field electromagnetic fields of a rotating half-wave dipole antenna. Theoretically, we have demonstrated that the far electromagnetic fields of a rotating half-wave dipole carry angular momentum in the term of ϕ- ϕ′, which is absent from the stationary half-wave dipole antenna. The term sin(kr−ωt+[ϕ−ϕ']) tells us that the electromagnetic wave propagates outward with the speed of light c(evidence from k= ω/c) from the dipole along the r axis and both electric and magnetic fields are spinning (oscillate with ω rad/s) and orbiting (rotating with ω0 rad/s) along the raxiswith the speed of light. The orbital frequency is evidence from the term ϕ−ϕ'=ω0 t−ω0 t'=ω0 r/c