Contents I. Introduction
The geometric structure on which different physical theories are based, and especially electromagnetism with Maxwell's equations, allows to express these equations in a discrete manner with respect to a pair of oriented and interconnected grids, one dual to the other, leading to the so-called discrete geometric approach (DGA) for computational electromagnetics. This idea has a solid physical and mathematical foundation, reflected in the scientific work of Prof. A. Bossavit with the understanding of the geometric properties of the finite element method [1]–[3], the work of Prof. T. Weiland regarding the finite integration technique [4], of Prof. E. Tonti with the cell method [5]–[7] and Prof. F. L. Teixeira about the formulation of the problem with differential forms [8], [9]. We will develop the treatment of admittance boundary condition in the framework of the DGA; such conditions are convenient when equivalent surface impedance models are developed to represent complex electromagnetic media in high frequency applications, such as the absorbers on the walls of anechoic chambers [10].
