2005 Fiscal Year Final Research Report Summary
Moisture and Ion Measurement on Soil by Attenuation and Propagation Velocity of Microwave
| Project/Area Number |
16360172
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Electron device/Electronic equipment
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| Research Institution | Shizuoka University |
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Principal Investigator |
OKAMURA Seichi Shizuoka University, Faculty of Engineering, Professor, 工学部, 教授 (20022014)
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| Project Period (FY) |
2004 – 2005
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| Keywords | sensor / moisture measurement setup / ion measurement system / soil / measurement / microwave / microstripline |
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| Research Abstract |
Measurements of Moisture content and ion concentration are important for agriculture especially in the field where plants are grown by irrigation. The good irrigation control is needed to keep the field good. In the case under bad irrigation the field does not only yield bad crops but also the field changes into bad land by the damage of salt that is distilled from the field. However, there is no proper sensor for the control.
This research has been done for the development of a new sensor to measure moisture content and ion concentration of soil, which can be used for the control. The new sensor researched in this project measures simultaneously the moisture content and ion concentration of the soil put on the sensor by utilizing the ability of microwaves of penetrating into soil and of detecting the difference between water and ion included in soil. It was realized by a new idea of using the attenuation and the phase shift of two microwaves of different frequencies, and also using the ratio of the attenuation to the phase shift.
It is constructed with three blocks of a microwave block, a sensing board block and a signal processing block. In the microwave block two waves of 2.6 and 8 GHz of 10 mW are used to measure moisture and ion in the soil put on the second block of a sensing board on which a microstripline is printed. The detected microwave signal of attenuation is divided by the signal of phase sift and transformed into moisture content and ion concentration of the soil by the signal processing block.
The resolutions of the sensors for moisture content and ion concentration are±1.6 % and±0.6 %, respectively. The kind of measured ion is now salt and soil sample is sand only.
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