Instruments and Systems: Monitoring, Control, and Diagnostics Annotation << Back Measuring Mass Flow of Gas and Liquid Matters in Pipelines G.N. AKHOBADZE Principles for measuring the stream density and velocity which use the resonant frequency and convection effect are proposed on the basis of microwave matter heating in a pipeline. Properties of dielectric materials under microwave heating are analyzed. An analytic dependence of the active power absorbed by the dielectric matter in the high-frequency field on the electric field intensity, loss factor, and frequency is demonstrated. A recommendation for determination of mass fl ow of a matter in the pipeline section being measured is given with account of stream characteristics and changes in the thermal conductivity of the material. Keywords: stream, flow, heat transfer, thermal conductivity, oscillation, electric field, temperature. DOI: 10.25791/pribor.03.2020.1158 Pp. 20-25.