For a nonlinear circuit in the steady-state, the solutions for all fundamental and harmonic-frequency components of the variables are interdependent. It is shown in the thesis that, with certain restrictions on the type of nonlinearity, the degree of interdependence is such as to allow separate, approximate solutions for fundamental and third-harmonic quantities. For these solutions the concept of a fundamental impedance which is a nonlinear function of one of its variables is used. Using this impedance a first approximation to the fundamental-frequency solution is obtained. An approximate equivalent circuit for the generation of third-harmonic quantities in the nonlinear elements is then developed using certain information of fundamental quantities from the first approximation along with some basic information of the nonlinear elements measured for a sinusoidal ateady-state condition. The results of the solution for third-harmonic quantities is used in a correction to the fundameLtal-frequency solution.

The methods described are best suited for use with network analysers (designed for linear problems);​ graphical end mathematical methods of solution are also domonr,trated. Some applications of the method to the analysis of complex electromagnetic circuits are given.

The method of analysis described in the thesis seeks to narrow the gap which appears to exist between the simple impedance methals of steady-state solution for linear networks and the relatively complex methods generally employed for nonlinear networks.