Magnetic field far from the origin

[OhNoYaDidn't]

Homework Statement

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:

Homework Equations

The magnectic field for a straight wire is mu0*I/(2*pi*r), and B=∇xA.

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?

 

[tech99]

Homework Statement

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:

Homework Equations

The magnectic field for a straight wire is mu0*I/(2*pi*r), and B=∇xA.

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?

Homework Statement

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:

Homework Equations

The magnectic field for a straight wire is mu0*I/(2*pi*r), and B=∇xA.

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?

Well I think at a great distance, we are talking about the magnetic field of the radiated EM wave. These fields, when radiated from a short conductor, will fall off inversely with distance, have a maximum at 90 degrees to the conductor and a radiation pattern which falls off with the cosine of this angle. Maybe this description will help?