Dual band microwave sensor for dielectric characterization of dispersive materials

A dual band microwave planar sensor based on the complementary split ring resonator (CSRR) is proposed for the characterization of dispersive materials. The proposed sensor is designed to work simultaneously at two industrial, scientific and medical (ISM) frequency bands viz., 2.45 GHz and 5.8 GHz, respectively. The sensor structure is realized using two CSRR unit cells loaded on the ground plane of a microstrip line. For accurate characterization of samples, a numerical model of the proposed sensor is developed, which provides the dielectric constant of the dispersive material under test in terms of the measured resonant frequency of each CSRR resonator. The designed sensor fabricated on a FR4 substrate is employed to measure number of dispersive dielectric samples in the two ISM bands with typical error of less than 5%.