Metal Detector Based on Lorentz Dispersion

Lorentz Dispersion regime is a narrowband spectral region characterized by a sharp resonance dip and an anomalous phase response. Due to its high dispersive nature, the Lorentz resonance is very sensitive to the changes in the physical dimensions of the resonators and the external perturbations approaching the resonant cavity. The proposed Lorentz structure consists of an open microstrip stub which contains a small gap. A metallic perturbation brought closer to the gap changes the electric field distribution leading to an effective increase in the stub's electrical size and a resonance shift. An experimental demonstration in the frequency range 1 to 1.5 GHz show that the relative resonance spectral shift correspond to the proximity of the metallic object.