Applications of a Twin Open Resonator System

The advantages and application of a twin open-resonator system in measuring frequency and small frequency intervals are described. An improvement in the tuning sensitivity and in the ease of adjustment is achieved by the controlled insertion of a thin dielectric sheet which provides vernier tuning. Application of the system has provided measurements of the extinction scattering cross sections of simulated hail particles when dry and melting. The technique has been extended to measure mutual scattering between pairs of spheres.