Field strength of a rectangular coil

Hi,

I could find out the field strength at the center of a rectangular coil.

Would you be kind to help me to find out the field strength of a rectangular coil at any distance, r from its center?

Thanks & Regards.

You can have a look to this:

nvlpubs.nist.gov/nistpubs/jres/105/4/j54mis.pdf

Thanks a lot. It helps me.