The Nyquist plot of a loop transfer funct ion G(jω)

The Nyquist plot of a loop transfer funct ion G(jω) H(jω) of a system encloses the (– 1, j0) point. The gain margin of the system is

Gain margin of the system for which Nyquist plot of a loop tr ansfer function G(jω) H(jω) encloses (– 1, + j0) point is less than zero.