A non-reflection-influence method for on-line measurement of permittivity using microwave free-space technique

This paper describes a new method for permittivity measurement using microw ave free-space technique. The general consideration is to measure the ampli tudes of transmission and reflection coefficients and calculate the permitt ivity from the measurement values. Theoretical analysis shows that the perm ittivity of the sample can be calculated solely from the measurement values of the amplitudes of transmission and reflection coefficients when the sam ple is prepared with so large attenuation that the multiple reflections bet ween the two surfaces of the sample can be neglected. Using this method, th e permittivity measurement can be performed without reflection influence, a nd on-line measurement of the permittivity becomes possible because the per mittivity can be measured instantaneously and without contact with the mate rial.