Magnetic Generation of a Group of Harmonics

A harmonic generator circuit is described which produces a number of harmonics simultaneously at substantially uniform amplitudes by means of a nonlinear coil. Generators of this type have been used for the supply of carrier currents to multichannel telephone systems, for the synchronization of carrier frequencies in radio transmitters, and for frequency comparison and standardization. A simple physical picture of the action of the circuit has been derived from an approximate mathematical analysis. The principal roles of the nonlinear coil may be regarded as fixing the amount of charge, and timing the charge and discharge of a condenser in series with the resistance load. By suitably proportioning the capacity, load resistance, and saturation inductance of the nonlinear coil, the amplitudes of the harmonics may be made to approximate uniformity over a wide frequency range. The sharply peaked current pulse developed by condenser discharge passes through the nonlinear coil in its saturated state and so contributes nothing to the eddy-current loss in the core. In this way the efficiency of frequency transformation is maintained at a comparatively high value for the harmonics in a wide frequency band, even with small core structures. The theory has also been adequate in establishing a basis for design, and in evaluating the effects of extraneous input components.