Negative L and C in Solid-State Masers

Abstract

The analysis of solid-state cavity masers is extended to include the reactive component of the paramagnetic resonance. This reactance is inverted (in opposition to Foster's reactance theorem). A two-cavity network makes use of this negative frequency dependence of reactance to obtain a broad-band flat-topped amplifier response. In verification of this theory a ruby maser has been built which has a 95-Mc bandwidth at 14-db gain and operates at 9000 Mc and 1.5°K. This performance is comparable to that of published, tapered magnetic field traveling-wave masers. General network limitations on cavity maser amplifiers are derived. Broadbanding techniques that have been published for parametric amplifiers are essentially equivalent. The tuning of the broad-band amplifier is critical. The same performance can be achieved in a unilateral transmission maser by using circularly polarized cavities, but the problem of circuit design and tuning with the increased number of parameters has thus far prevented successful operation.