A Hertzian dipole is a short conducting wire carrying an approximately constant current over its length l. If such a dipole is placed along the z-axis with its midpoint at the origin and if the current flowing through it is i(t) = I0 cos t, find
(a) The retarded vector potential A (R, at an observation point Q(R, in a spherical coordinate system, and
(b) The magnetic field phasor H(R, Assume l to be sufficiently small so that the observation point is approximately equidistant to all points on the dipole; that is, assume that R ≈ R.