This paper presents a general technique to apply excitations in the framework of discrete geometric numerical methods using
dual grids, such as discrete geometric approach and finite integration technique. The technique overcomes some limitations of the
impedance boundary condition we proposed in a previous work, especially when dealing with waveguides, where specific excitation
modes must be applied. The proposed approach is based on a scattering/total field decomposition, which, if needed, allows to study
scatterings due to objects.
