1. The problem statement, all variables and given/known data An important result in the theory of antennas, is that if a current passes through the ZZ axis, the magnetic field far from the origin can be expressed in spherical coordinates, using only one componente of the magnetic vector potential. Prove that: 2. Relevant equations The magnectic field for a straight wire is mu0*I/(2*pi*r), and B=∇xA. 3. The attempt at a solution This was in my exam last week, and i have no idea how to solve it... I've tried stating with the magnetic field of a straight wire, but i don't know how to relate that with the curl of A. Can you guys please help me out?