Clockwise nature of Nyquist locus of stable transfer functions

Abstract

F(s) is a finite proper rational function with real coefficients and all its poles in the interior of the left half-plane. The Nyquist locus of F(s) is the mapping F(s), s = jω, with ω in [0, ∞). It is shown that the Nyquist locus of F(s) is clockwise at all ω in [0, ∞).