Noise performance of an overloaded maser amplifier

The noise output and noise factor F of a simplified model of a maser is studied as a function of the ratio g/G of small-signal gain g to actual gain G. The noise output drops rather sharply as g/G is increased. The noise factor, however, increases only very slowly from its value of F = 1 at g/G = 1 to F = 1 + ½ ln g for a totally overloaded maser (G = 1).