Ricerc@Sapienza

In this paper, preliminary results of variations as a function of applied pressure in the reflection coefficient of a planar patch resonator, placed in contact with cultural heritage stone materials, will be presented. The general aim of the experimental project is to correlate the resonant frequency of the planar sensor, for the different pressures applied to the resonator, with the different levels of water content θv of the tested stone material.

In this work, a noninvasive microwave-based system for monitoring water content of Cultural Heritage stone
materials is presented. In particular, by placing a planar resonator in contact with the stone sample, an experimental
relationship between resonant frequency and water content is obtained.
To verify the suitability of the system, experimental tests are carried out on several types of stones: gentile;
leccese; carparo; red brick; and red brick fabricated at high temperatures. The first three types of stones are

In this work, the assessment of water content of building materials, to be used for moisture content monitoring of Cultural Heritage structures is addressed. To this purpose, different methods and probes were comparatively used to infer, noninvasively, the relationship between the water content of stone materials and the reflection properties at microwave frequency of the material. In particular, three types of probes were used: an open-ended coaxial probe; a patch resonator; and an open-ended waveguide.

Dielectric permittivity-based measurement techniques are establishing themselves as attractive solutions for assessing the moisture content of historic masonry materials. The relative simplicity of the measurement principle and the inherent adaptability to diverse operating conditions are two of the most notable features of these techniques. In spite of these specific advantages, however, there are still some aspects that hinder the widespread use of permittivity-based moisture content measurement systems, and make their standardization difficult.