Measurement and modelling of soil dielectric properties as a function of soil class and moisture content

Kabir, Humayun, Khan, Mohammad Jamal, Brodie, Graham, Gupta, Dorin, Pang, Alexis, Jacob, Mohan V., and Antunes, Elsa (2020) Measurement and modelling of soil dielectric properties as a function of soil class and moisture content. Journal of Microwave Power and Electromagnetic Energy, 54 (1). pp. 3-18.

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In this study, four textural classes of soil (Clay, Clay Loam, Loam, and Loamy Sand) were used to investigate the dielectric properties of soils, using a vector network analyser with an open-ended coaxial probe kit at room temperature (25 ± 2°C) in the 700–7000 MHz microwave frequency range. Four levels of soil moisture content (oven dry, 33% field capacity, 66% field capacity and 100% field capacity) were maintained to perform the experiment with three replication and three observation each. The results showed that, with increasing soil moisture, from oven dry conditions to 100% field capacity, both the real (Dielectric Constant) and imaginary (Loss Factor) components of the dielectric properties increased; however, the responses were not linear. The dielectric properties of oven dry soils were very low compared with the soils with higher moisture content. Therefore, soil moisture was the major contributor to the dielectric behaviour of soil. The dielectric properties of sandy soil were much lower than the other soils; however, the dielectric loss factor of the Dookie clay soil was higher compare with the other soils. Models were developed to explain the dielectric properties of soils as a function of frequency and moisture content. The goodness of fit (r2) for these models varies between 0.952 for the Dookie Sandy Soil to 0.997 for the Dookie Loam Soil, suggesting that these models were adequate to describe the dielectric properties of these soils over the range of frequencies and moisture contents assessed in this study. Another model was developed to estimate the expected penetration depth of electromagnetic waves in these soils, based on the model of the dielectric properties. It was clear that penetration decreases with both frequency and moisture content. Low frequencies penetrate further into the soils than higher frequencies. Similarly, dry soils allow further penetration than moist soils.

Item ID: 63988
Item Type: Article (Research - C1)
ISSN: 2472-4041
Keywords: Soil, dielectric, moisture, soil classification
Copyright Information: © 2020 International Microwave Power Institute
Date Deposited: 05 Aug 2020 03:29
FoR Codes: 40 ENGINEERING > 4016 Materials engineering > 401699 Materials engineering not elsewhere classified @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970109 Expanding Knowledge in Engineering @ 100%
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