Permittivity of wood as a function of moisture for cultural heritage applications: a preliminary study

In this work, the evaluation of moisture content in historic wooden objects starting from permittivity measurements is investigated. For this purpose, a WR430 waveguide with a 1.7-2.6 GHz range was used to estimate the complex permittivity correlated to different moisture levels. Experimental tests were carried out on poplar (Populus nigra L.), a wood typically used in central Italy in the thirteenth-sixteenth centuries as a painting support. For the considered measurement system, experimental results and calibration curves are reported.