Demagnetizing fields of planar magnetic film structures with one infinite dimension

Structures made of infinitely long planar strips of magnetic film whose infinite dimensions are all parallel are considered, and the field needed to magnetize them to a given extent normal to that dimension is specified. An exact analytic solution is given for partially saturated coplanar films. Some useful analytic approximations and a computer program are described for solving more general structures, including results for a sandwich of a current-carrying conductor between two parallel film strips.