Use of the method of moments to find the charge densities and capacitances of a shielded twisted pair transmission line

The surface charge densities and associated capacitances of a shielded twisted pair transmission line are found for quasi static conditions, under balanced and longitudinal excitations. The unknown charge density is expanded in a Fourier series. The series is used as basis functions for a method of moments solution to find the unknown series coefficients. This paper describes the geometric structure and the formation of the integral equation that describes the potential distribution as a function of the unknown charge densities. The simplifying approximations made are pointed out, as well as the limitations to the solution caused by the approximations.