Low-frequency stability of the Razor blade tested MFIE

Razor blade testing schemes have been proposed in the past for both the EFIE and MFIE. The regularity of these testing functions is, strictly speaking, not sufficient for the discretization to be conforming. However, as will be shown in the contribution, it does yield physical solution currents at low frequencies. This is similar to the low-frequency behavior of the mixed discretization of the MFIE. Nevertheless, in this testing scheme, there is no refined mesh, the impedance integrals are triple integrals instead of quadruple integrals and, in addition, the testing functions are constant instead of linear on their support.