Electromagnetic properties of coal using microstrip and an algorithm based on the Nicolson-Ross-Weir method

Abstract

The work implements an experimental methodology to find the dielectric parameters: electrical permittivity, effective permittivity, magnetic permeability, conductivity, absorption coefficient, impedance, and loss tangent of bituminous coal from the municipality of Morcá and Tópaga belonging to the Sogamoso-Jericó sub-basin of the Guaduas formation, one of the most important coal reserves in Colombia. The methodology, known for its efficiency, includes constructing a microstrip-type circuit, measuring scattering parameters or S-parameters at frequencies between 300 kHz and 1 GHz with a vector network analyzer, and extracting electromagnetic properties using the Nicolson-Ross-Weir algorithm. The implemented algorithm allowed us to see the behavior of the coal in a fraction of the ultra-high frequency band and to find quickly and easily the approximate values of the parameters as a function of frequency, which are very important for investigations in mathematical modeling and computational electromagnetics. The results show that the real and imaginary components of the relative dielectric permittivity decrease with increasing frequency, and the absorption coefficient and the loss tangent of the coal increase as a function of frequency, indicating that the coal behaves as a dissipative dielectric.