a plot of the image of this path with respect to the open-loop transfer function F ( s )
a plot of the magnitude of the amplitude gain and phase shift of a system for sinusoidal inputs
a polar plot of the frequency response function of a linear system
A method used to assess system stability in which plot of the real part versus the imaginary part of the frequency response function is made. For a single-degree-of-freedom system, the Nyquist plot is a circle. The Nyquist plot represents a frequency response function by graphing the "real" part versus the "imaginary" part. In the Nyquist plot, a resonance shows up as a circle, but there is no indication what its frequency is -- the Nyquist plot is like sighting down the frequency axis at the real and imaginary parts of the function.
A plot of real versus imaginary spectral components that is often used in servo analysis. Should not be confused with a polar plot of amplitude and phase of 1x vibration.
A Nyquist plot is used in automatic control and signal processing for assessing the stability of a system with feedback. It is represented by a graph in polar coordinates in which the gain and phase of a frequency response are plotted. The plot of these phasor quantities shows the phase as the angle and the magnitude as the distance from the origin.