Semantics of the irrotational component of the magnetic vector potential, A

Electric and magnetic fields of wave problems are, usually, calculated from derivatives of the scalar potential, /spl phi/, and the vector potential, H=1/μ curl A and E=-grad/spl phi/-(/spl part/A)/(/spl part/t). The potentials /spl phi/ and A are obtained as solutions of wave equations in the so-called Lorentz gauge. However, in this gauge, the familiar semantics of the potentials /spl phi/ and A have significantly changed. This is particularly true for A, which, usually, manifests itself as a rotational field, and which is now augmented by an irrotational field A/sub irr/. This irrotational field component can be clearly explained if the magnetic vector potential wave equation is derived in the Coulomb gauge. Simultaneously, this derivation leads to a better understanding of the fields in the environment of a dipole antenna. We derive the wave equation of the magnetic vector potential both in the classical Lorentz gauge and in the Coulomb gauge. Subsequently, this will allow us to clearly point out the differences between the Coulomb gauge and the Lorentz gauge. In between both derivations, we elaborate the current-density fields in the environment of a dipole antenna in the non-stationary case.