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Non‐destructive prediction of forage crop moisture contents using microwave transmitted signals with a microstrip transmission line sensor
Author(s) -
Matsuo Morinobu,
Osada Akira,
Kon Seitaro
Publication year - 2020
Publication title -
grassland science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.388
H-Index - 19
eISSN - 1744-697X
pISSN - 1744-6961
DOI - 10.1111/grs.12271
Subject(s) - water content , silage , microwave , moisture , forage , microstrip , amplitude , linear regression , environmental science , materials science , soil science , agronomy , mathematics , composite material , physics , optics , biology , statistics , geology , geotechnical engineering , quantum mechanics
This paper describes a non‐destructive method for using microwave transmitted signals to measure the moisture content of silage wrapped with plastic films. To collect measurements by a vector network analyzer, each bag of silage was placed on a microstrip transmission line without destruction of the films. Both rye and corn were tested. Significant linear relationships between the amplitude change (Δ A ) and phase shift (Δ φ ) were obtained except for with fully dried corn, and the corresponding R 2 values between Δ A and Δ φ were 0.8 or greater. The slopes, which represent the ratio of phase shift to amplitude change (Δ φ –Δ A ratio), depended on the frequency and moisture content. R 2 values between the Δ φ –Δ A ratio and moisture content of rye and corn were greater than 0.8 at the frequency of 3.6 GHz or above except for with fully dried corn samples. At 3.6 GHz, significant linear relationships between the Δ φ –Δ A ratio and moisture content were obtained for rye and corn. Furthermore, the slope and intercept of the linear regression line between the Δ φ –Δ A ratio and moisture content of rye were not significantly different from those of corn. These results illustrate the potential of the non‐destructive moisture content measurement method with microwave transmitted signals for silage materials with high moisture contents.