A diversity of stellar classes has been detected to be prolific sources of low-level, “quiescent” microwave radiation. This emission is, in most cases, attributed to the persistent presence of mildly relativistic electrons in the coronae. Frequent or continuous particle acceleration is required to maintain a high level of gyrosynchrotron emission. In this paper, observations relevant to our understanding of quiescent microwave emission from stars are reviewed, with emphasis on nondegenerate, late-type stars. Though the nature of the acceleration process remains unknown, a large amount of crucial information is presently available, in particular observations of timescales of slow variations, estimates of particle energies, model calculations based on spectral observations, and correlative studies with soft X-ray emission.
Subject headings: acceleration of particles — radio continuum: stars — stars: activity — stars: coronae — stars: late-type — stars: magnetic fields