Microwave Doppler-Effect Particle Flowmeter: Approximate Signal Theory

Approximate expressions for the expected values of the microwave back-scattered Doppler radar signal parameters due to particle flows are derived in terms of the particle properties and flow-field configuration using standard dielectric mixture, electromagnetic and stochastic process theory. The experimental results obtained for barley grains of different moisture contents and water drops involving three different free-space flow-field geometries were in approximate agreement with the theory. This approach is simpler to apply to Doppler-effect flowmeter design than multiple scattering theory is, and will probably be more accurate when applied to a closed flowmeter system for which the flow-field geometry may be more easily accurately defined.