Determination of dielectric permittivity of concrete using microwave dielectric-loaded dual-waveguide sensor for infrastructure health monitoring

In this paper, a dielectric-loaded microwave dual waveguide sensor (DWS) has been used to determine the complex dielectric permittivity of fresh concrete using measured magnitude of reflection coefficient and transmission coefficient. The proposed sensor consists of two standard X-band (8.2 GHz-12.4 GHz) rectangular waveguide sections and a metal plate as a common flange, which can be attached to a concrete specimen. The simulated magnitudes of reflection and transmission coefficients obtained with a guessed preset value of dielectric permittivity of concrete specimen are compared with measured ones until predefined accuracy level is achieved. The complex dielectric permittivity of the first-day concrete is determined. It is shown that its value provides a good agreement between measurement and simulations results.