Application of Layered Medium Green´s Function in Low Frequency Models for Numerical Solutions

An accurate and efficient technique is presented for obtaining numerical solutions of microstrip structures at low frequencies. In this approach, a new form of the electric-field spatial-domain Green´s function is used in a symmetrical form that simplifies the discretization of the integral equation using the method of moments (MoM). Hence, a Helmholtz decomposition of the unknown currents is achieved by applying the loop-tree decomposition of the currents. However, the MoM matrix thus obtained still cannot be solved efficiently by iterative solvers due to the large number of iterations required. Consequently, a permutation of the loop-tree currents by a connection matrix is proposed to arrive at a current basis that yields a MoM matrix that can be solved efficiently by iterative solvers