Wireless Sensing of Permittivity for Cultural Heritage Monitoring Using a Passive SRR

Monitoring water content in cultural heritage materials through non-invasive and easy-to-use measurement systems allows the enhancement of artistic patrimony conservation activities. In this study, the response of a passive split ring resonator (SRR) used to monitor the dielectric characteristic of a material under test, when excited through an antipodal Vivaldi antenna operating close to the resonator, is analyzed through numerical simulations and then assessed by measurements. Our results reveal the possibility of monitoring the moisture content in materials largely used in artistic artifacts, such as wood and stone, through measurements of the SRR resonance frequency, which is directly related to material dielectric characteristics.