Passive chipless wireless pressure sensor for Harsh and reflective environments

Abstract

This paper presents investigations on a passive chipless wireless pressure sensor to enhance tool life prediction in smart milling machines. High reflective environments in terms of radar clutter are investigated and benefits of using the time gating technique are discussed. Moreover, due to the proposed highly robust design, the sensor can be applied in areas with high temperatures and strong vibrations. The working principle is based on a dielectric resonator which is metal coated on its lateral surface. Perturbing the resonance mode with a metal membrane in vicinity of the resonator leads to a pressure dependent resonance frequency. A broadband interrogation signal is used to determine the resonance frequency, which is represented by a notch in the backscattered spectrum. The pressure sensitivity and pressure range is configurable by using different membrane and spacer thicknesses, respectively. Furthermore, the sensor operates in the frequency range from 20 GHz to 23 GHz with read-out ranges up to 150 cm.