Determination of electromagnetic attenuation characterization of some hollow building materials based on Free-Space transmission measurements at lower microwave frequency band

• Attenuation characteristics of bims block and clay brick samples in 1–3 GHz frequency band. • Free-space transmission measurement techniques for determining the electromagnetic characteristics of dielectric materials. • Application of time-gating and Hermitian processing for the system transfer function of electromagnetic propagation . In this study, two complementary methods based on free-space transmission techniques with the usage of time-gating signal processing schemes are proposed in aiming to characterize the electromagnetic (EM) characteristics of hollow building materials, namely, bims block and clay brick. Based on open-field experiments at the frequency band from 1 to 3 GHz, estimation of EM attenuation constant was achieved by two different ways; direct estimation from measured data and estimation based on single-pass modelling and low-loss material approximation. With this approach strategy, various EM parameters of EM attenuation, electric conductivity, loss-tangent, and the relative electric permittivity can be determined. It is shown that both techniques yield almost identical results of EM attenuation within the investigated band. Once the EM attenuation characteristics of these materials are successfully predicted, a rubble detection radar application is also demonstrated to show the usage of the obtained attenuation values of bims block and clay brick materials.