Nyquist contour

Nyquist contour

[′nī‚kwist ‚kän‚tu̇r]
(control systems)
A directed closed path in the complex frequency plane used in constructing a Nyquist diagram, which runs upward, parallel to the whole length of the imaginary axis at an infinitesimal distance to the right of it, and returns from + j ∞ to -j ∞ along a semicircle of infinite radius in the right half-plane.