Also found in: Acronyms.
the dependence of the amplitude of a sinusoidal oscillation on its frequency at the output of an apparatus. The characteristic is measured by applying an oscillation of constant amplitude and variable frequency to the input of the apparatus in the linear mode. The amplitude-frequency characteristic is often called simply the frequency characteristic. For ease of visualization it is plotted in the form of a curve; the amplitudes or relative amplitudes are laid off along the vertical axis (often in decibels), and the frequencies (sometimes on a logarithmic scale) along the horizontal axis. In electrical engineering, radio technology, and other technical fields, the amplitude-frequency characteristic yields various parameters (frequency pass band, selectivity, and others) by which the operation of apparatus and devices can be assessed.