Low frequency microstrip analysis using the spectral domain approach and the variational method

This paper addresses the solution for the open structure microstrip line. This paper attempts to find the relationship between the variational method and the spectral domain approach at very low frequencies. In this paper, the Green´s functions for the spectral domain approach at low frequencies are derived. The Galerkin´s method is used to obtain the formula to calculate the effective relative dielectric constant. At DC, the transverse current density is zero. However, to get the accurate effective relative dielectric constant, both the longitudinal current density and the normalized transverse current density should be used.