Microwave Characterization of Powders Using Multiresonance Cell

Abstract

This paper describes the microwave characterization of powders using a multiresonance cell supporting TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10p</sub> modes in a rectangular cavity. An identification of the resonating modes excited in the cell has been done in order to extract the real and imaginary parts of a complex dielectric constant of the material under test. Calibration of the cell has been performed using the empty resonator. An error analysis was employed in order to estimate the uncertainty caused by coupling elements needed to connect the measuring cell with a network analyzer. The CST Microwave Studio solver was used to evaluate degrading measurement accuracy caused by a presence of coupling elements. Comparison of the measured data with 3-D electromagnetic simulation has demonstrated a good agreement. The validation of the method described has been done for the α-lactose monohydrate powder as a tested material at X-band. The role of density of powder has been estimated too. The same approach can be easily extended to the microwave characterization of other powder materials.