Microwave dielectric measurements in different varieties of rapeseed-mustard seeds in powder form

Abstract

Effect of packing density on dielectric parameters, relaxation time and conductivity of three different varieties of rapeseed-mustard seeds in the form of powders has been studied at x-band (8.93 GHz) microwave frequency. Experimental results on powders of different relative packing fractions (δ_r) have been used to obtain transformation to 100% solid hulk using correlation formulae of Landau-Lifshitz-Looyenga and Bottcher. In case of seed grains like rapeseed-mustard where it is not possible to define solid bulk exactly, the authors have assumed the finest crushed closely packed assembly of the seed grains as solid bulk for the comparison of these correlation formulae between powder and solid bulk. This assumption

works well as there is fair agreement between the calculated values of dielectric parameters and the values obtained experimentally for solid bulk. Appreciable agreement between the experimentally obtained values and the theoretical values obtained by Bottcher's and Landau-Lifshitz-Looyenga's formulae shows large cohesion in the particles of rapeseed-mustard

powders under investigation, serving as a continuous medium.