Electromagnetic Nondestructive Material Characterization of Dielectrics Using EBG Based Planar Transmission Line Sensor

In this paper, a novel noninvasive electromagnetic method of characterization of the electrical properties of dielectrics is presented. A planar microstrip transmission line method has been employed to measure the complex permittivity of the dielectric materials. The transmission line carrying microwave signals is bridged on both sides by electromagnetic bandgap structures which notches only 2.4 GHz. The electrical properties are measured at this frequency. The dielectric is loaded on this transmission line. The notched frequency information and the magnitude of the transmission response are observed using the computer simulation technology for various materials whose real part of permittivity and loss tangent values are known. Relation for finding the permittivity of the dielectric based on the observed response has been derived using curve fitting. The imaginary part of the permittivity of the dielectric is calculated from the loss tangent. The accuracy of the numerical model is developed and the efficiency of the testing method is tested through the measurement of various materials and the goodness of fit of the derived equation is verified. The proposed model exhibits an R -square measure of goodness of fit of 99.83% for the real part of permittivity and 96.67% for the imaginary part of permittivity.