MoM-Based Computation of Multionductor Transmission Line Per-Unit-Length Parameters
The main task of the program CONMTL is the computation of the per-unit-length parameter matrices L’, C’, G’and R’ for multi-conductor transmission lines of arbitrary cross section. The program is based on a method of moments (MoM) technique by means of which a 2D integral equation is solved numerically for electrostatic problems. This integral equation is derived from the 2D Poisson’s equation of electrostatics. In a first step equivalent surface charge distributions are computed by discretizing both conductor and dielectric boundaries into appropriate numbers of straight segments. Over each segment a constant charge basis function is defined. Boundary conditions to be fulfilled are the constant potential on metal conductors and constant normal electric flux density on dielectric boundaries. In this way the integral equation can be converted into a linear system of equations. Solving this matrix equation provides an approximation of the overall charge distribution, both on the metal parts and on dielectric boundaries. This known charge distribution is necessary for the subsequent computation of the mentioned transmission line parameters. Comprehensive possibilities for visualizing the equivalent charge distribution on all cross sectional transmission line parts as well as the E field distribution exist for quickly checking the validity of the numerical solution. Given the length of a transmission line the corresponding Y-parameter matrix can easily be computed using well-known expressions from multi-conductor transmission line theory. Finally S-parameters are provided as a function of frequency.