The application of the point matching method to the analysis of microstrip lines with finite metallization thickness

The characteristics of a shielded microstrip line with finite metallization thickness are calculated using the point matching method (PMM). The advantage in this case is that the method does not depend on a special geometry of the strip metallization. The approach used is based on satisfying the boundary conditions at discrete boundary points. Numerical results are presented to assert the validity of this approach in cases of large values of strip width-to-thickness ratio. It is found that an increase in the strip thickness is always associated with difficulties in convergence. The examples presented call attention to the necessity of proving the validity of the obtained solutions by other criteria. This is because good convergence behavior of the effective dielectric constant does not always guarantee the correct characteristic impedance or field distribution. In particular, the field distribution is considered as a reliable check for the numerical results