Using RWG functions (triangular patches), the spherical surface is only approximated. The influence of this error in model on the resonance frequency is studied below on examples of three different mesh grids. For the poorer one (at the top), the relative error between numerically and analytically calculated characteristic eigenvalues is huge. Still, it can be somehow compensated if we assume that the discretization grid has (smaller) equivalent radius. However, the compensation is far from being perfect. In the cast that a finer mesh is used (at the middle), the error is smaller since the mesh grid is more conformal with the spherical shell. Finally, the finest mesh (at the bottom) embodies only small errors which are almost completely eliminated by recalculating numerical model (in fact, we decreased size of analytical sphere as this is much more straighforward for our calculation). In all cases, the influence of degrees of Gaussian quadrature (1st, 4th, 8th order) is depicted.
/Edited 17. 07. 2017, MC/