A frequently recurring problem in induction device theory involves the determination of the input wave impedance to a device. This is commonly done by solving for the field components. In this paper, a completely different method based on the scalar Riccati equation is described. It is shown that the wave impedance can be obtained by the numerical integration of a Riccati-type differential equation, having wave impedance as the unknown variable. This is illustrated with three simple models each having an unknown field distribution in one direction only. Extensive computer testing was carried out and the results obtained were found to agree very closely with published analytical methods. The method is very simple, easily programmed and avoids the use of higher transcendental functions.