Quantum mechanics

Moisture

Engineering

Aerospace engineering

Statistics

Geotechnical engineering

Materials science

Soil moisture sensor

Transponder (aeronautics)

Power (physics)

Ultra high frequency

Calibration

Antenna (radio)

Geology

Capacitive sensing

Physics

Mathematics

Electronic engineering

Environmental science

Remote sensing

Composite material

Chip

Water content

Landslide

Electrical engineering

Sensors

Two solutions for UHF RFID tags for soil moisture sensing were designed and are described in this paper. In the first, two conventional tags (standard transponders) are employed: one, placed close to the soil surface, is the sensor tag, while the other, separated from the soil, is the reference for system calibration. By transmission power ramps, the tag's turn-on power levels are measured and correlated with soil condition (dry or wet). In the second solution, the SL900A chip, which supports up to two external sensors and an internal temperature sensor, is used. An interdigital capacitive sensor was connected to the transponder chip and used for soil moisture measurement. In a novel design for an UHF RFID tag the sensor is placed below the soil surface, while the transponder and antenna are above the soil to improve communication. Both solutions are evaluated practically and results show the presence of water in soil can be remotely detected allowing for their application in landslide monitoring.

Two Solutions of Soil Moisture Sensing with RFID for Landslide Monitoring