A new microstripline-type moisture sensor for heavily wet tea leaves

Abstract

This paper describes a new sensor for high moisture measurement in producing green tea. The sensor is based on the microwave transmission technique. It uses a microstripline, on which tea leaves under test are overlaid. A microwave signal at 3 GHz was transmitted along the line, and attenuation and phase shift of the wave were measured. The moisture content of the leaves was calculated by a new idea of using the ratio of two signals corresponding to the attenuation and the phase shift. The sensor measured a moisture content range from 155 to 320% on a dry basis.

A radio frequency device for measurement of minute dielectric property changes in microfluidic channels

“…4 It has also been developed for bioanalysis. 3,5,6 Sensors that are based on measuring dielectric property changes, such as surface moisture sensors, 7,8 have been demonstrated as well. In comparison with other approaches, measuring dielectric properties and their changes ͑i.e., dielectric spectroscopy͒ electronically has several advantages.…”

Electromagnetic moisture measurement

“…In this context electromagnetic techniques over the past decades have proven convenient tools for the study of diverse substances. We mention grain and seed [522,[801][802][803][804][805][806][807]; coffee [805], in-shell and unshelled peanuts [808,809]; ice lettuce [810], tobacco slices [811], and tea leaves [812,813]; seafood [653,[814][815][816]; rapeseed [811], oil palm fruit [817][818][819], and hevea rubber latex [820] and also cotton bale [821] and biofuels [822].…”

Monitoring Moisture Content for Various Kind of Tea Leaves in Drying Processes Using RF Reflectometer-Sensor System

“…The first type of sensor is one pair of horn antennas and its moisture measurement is based on the free-space transmission techniques [16,17]. The second type is a microstrip line sensor which is used for near field measurement [18,19]. Both methods have advantages and disadvantages, respectively.…”