Complex Wave Forms

Author: J.B. Hoag

In electronic circuits, the currents and voltages are often of complicated wave form rather than simple sine curves. However, these can be thought of merely as the sum of a number of simple sine curves. Some of the combinations encountered in practice are shown in Fig. 4 D.

Fig. 4 D. Complex waves and their composition

The lowest frequency f is called the fundamental or first harmonic. The wave of twice this frequency is the second harmonic. The 3f wave is the third harmonic. Extremely complex waves may contain as many as 400 harmonics each of appreciable strength compared with the fundamental. The existence of various harmonics of different strengths makes the difference between the " qualities " of the musical notes sounded by different musical instruments.

It is possible by mathematical analysis (the study of Fourier Series), and also by means of machines called harmonic analyzers, to resolve into its harmonics any periodically repeating wave, no matter how irregular and complex it may be.