Recent Results Obtained from Open Resonator Measurements Which Relate to Fundamental Processes in Propagation

Recent measurements taken in three open resonator systems operating at frequencies in bands around 10GHz, 35GHz and 70GHz and with the aid of a microcomputer which manages the result taking have allowed each of the following to'be achieved:- a) recording of detailed results for the extinction cross-section (total loss cross-section, ^σext) of a series of spherical particles of hard ice, when dry and during melting. b) determination, using the millimetric-wave resonators, of the refractive index and loss tangents of dispersions of fine particles, for example of a dispersion of very small water particles, oil-based smoke and sand. c) a study to assess where mutual scattering effects might be of importance, for example dunrng shedding of water particles from hail and snow particles. In each case, (a), (b), (c) the relationship of the measured data to propagation studies is discussed.