Spherical near to far field transformation

Readro

Hi all,

Suppose I have measured an antenna's nearfield pattern and have a set of data f(theta, phi), where theta and phi are spherical coordinates, at a distance r from the antenna (we'll assume that the antenna is a point source to make it easier). How would I go about transforming this data to get the antenna's farfield pattern? I've tried searching the net for this but haven't found anything useful for spherical measurements. I understand that planar measurements use a 2D fourier transform but the spherical coordinates complicate things a bit.

FYI, I have a degree in mathematics but it's been a while now so I might be a little rusty.

Readro

I hate to bump a post, but does anyone have any thoughts or ideas?