Design of a Microwave Heating and Permittivity Measurement System Based on Oblique Aperture Ridge Waveguide

Abstract

In this paper, an oblique aperture ridge waveguide operating at 2450 MHz is proposed, and, using the ridge waveguide, a permittivity measurement system is constructed which can measure the permittivity of materials during microwave heating. The system calculates the amplitudes of the scattering parameters by using the forward, reflected and transmitted powers of the power meters, and it reconstructs the permittivity of the material by combining the scattering parameters with an artificial neural network. The system is used to measure the complex permittivity of mixed solutions of methanol and ethanol with different ratios at room temperature, and the permittivity of methanol and ethanol with increasing temperature, from room temperature to 50 °C. The measured results are in good agreement with the reference data. The system allows simultaneous measurement of the permittivity with microwave heating and provides real-time, rapid changes in the permittivity during heating, avoiding thermal runaway and providing a reference for applications of microwave energy in the chemical industry.

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“…One can divide microwave sensing methods into two broad categories, resonant sensors and non-resonant sensors. Transmission lines [6][7][8] and waveguide structures 9,10 are the most prevalent configurations utilized in non-resonant sensing approaches. For instance, Gou et al 10 measured complex permittivity of ethanol and methanol mixtures using an oblique aperture ridge waveguide.…”

“…Transmission lines [6][7][8] and waveguide structures 9,10 are the most prevalent configurations utilized in non-resonant sensing approaches. For instance, Gou et al 10 measured complex permittivity of ethanol and methanol mixtures using an oblique aperture ridge waveguide. Interestingly, the proposed structure had the ability to measure the binary mixtures' properties during microwave heating at various temperatures.…”