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Calculation of the near-zone fields (fields at the vicinity of the unknown currents) is done at the post-processing stage and in a Cartesian coordinate systems. These calculations involve doubly infinite spectral-domain integrals, which are computed numerically. As was mentioned earlier, [[EM.Cube]]'s planar MoM engine rather uses a polar integration scheme, where the radial spectral variable k<sub>ρ</sub> is integrated over the interval [0, Mk<sub>0</sub>], M being a large enough number to represent infinity, and the angular spectral variable t is integrated over the interval [0, 2π]. You also saw some of the numerical [[parameters]] related to this spectral-domain integration scheme.
{{Note|When the observation plane is placed very close to the radiating J and M currents, the Green's functions exhibit singularities, which translate to very slow convergence or divergence of the integrals. You need to be careful to place field sensors at adequate distances from these radiating sources.}}