Off-Axis Fields due to One or Two Coils
It was modified by me (Sam) to use units of inches instead of meters (OK, so I'm old-fashioned or something. but inches are more convenient for what I'm doing) and two coils wound using multiple layers with multiple turns and wire of finite diameter. This includes the special cases of solenoids (l=1) and pancakes (t=1). The separation also allows for the special cases of the Helmholtz and figure-eight coils. The math may not be precisely exact but should be close unless I screwed up a sign or two. ;-)
Enter the mean radius of the coils, current in coil 1 (i1) and the relative current in coil 2 (i2 = the value multiplied by i1); total number of layers (l), number of turns/layer (t), and wire diameter (d); axial separation (xs) and radial separateion (rs); and the axial (x), radial (r), and offset (o) of the measurement point. Then click "Calculate Fields" to determine the resulting fields for each coil individually and the net field from both.