Density Dependence of Permittivity of Green Tea at 9.4 GHZ and Moisture Content Determination

Anew method is proposed for measuring permittivity by using the amplitudes of the transmission and reflection coefficients, and it was proven valid by experiment. Using this method, the density dependence of the permittivity of green tea was investigated. Both the real and imaginary parts of the permittivity were linearly related to the density when the moisture content was constant. The ratio of the real part minus one over the imaginary part of the permittivity is a moisture content fitnction independent of density. This function was valid for moisture content determination in the range below 50% (d.b.). In the range above 50 %(d.b.), the moisture content can be determined using the function of the imaginary part of the permittivity divided by the density.