Modal-expansion analysis of a monopole in reverberation chamber

In this paper, a modal expansion method is proposed to compute the field distribution inside a reverberation chamber excited by a monopole. The electromagnetic fields are expanded using modal functions derived from Helmholtz equation. The continuity conditions of tangential field components at regional interfaces are transformed into four matrix equations through the mode matching (MM) process. Another two matrix equations are obtained using the point matching (PM) method by imposing the boundary conditions on the four side walls. With those six matrix equations, all the unknown expansion coefficients are determined. This technique takes advantage of the orthogonality of the modal functions, and thus the obtained matrix is block-diagonal, which is easy to be inverted. Furthermore, discretization of the whole chamber is avoided so that the problem scale is greatly reduced. Therefore, the proposed method appears to provide a rigorous and efficient analysis of RC excited by a monopole antenna.