In order to further illustrate the concept of phase-similar MPMR's, consider an MPMR 600 in which elements 620a and 620c have axial magnetizations M0 and ?M0, respectively. Next, consider a different MPMR 600* (not shown) which is the same as MPMR 600 in all respects, except that elements 620a* and 620c* have radial magnetizations 2M0 and ?2M0, respectively. Since MPMR 600 can be transformed into MPMR 600* by a common rotation of the magnetic moment by 90° in the r-Z plane followed by multiplication by a common scale factor of two, the two MPMR's are considered to be phase-similar. For each ring one may define the effective strength of the ring by the magnitude of the volume averaged r-Z projection of magnetization vector divided by the largest magnetization magnitude of all permanent magnet phases. The parameter has a value between 0 and 1; and has the qualitative meaning of how effective a ring produces a magnetic field nearby. When two rings are not phase similar, they may have different relative effective strengths and different contributions to the magnetic field.

Generally, adjacent elements in an MPMR are held together by mechanical means or by adhesives. If the total volume occupied by adhesive layers is small, e.g. less than 1% of the total volume of the ring, then the adhesive layers need not be treated as an additional phase for the purpose of magnetic field calculations. Small adjustments in the segments positions and angles may be carried out to compensate for the segments imperfections and residual inhomogeneity.