Dielectric resonator antenna integrated sensors for characterization of concrete

This paper presents a two-antenna setup based on dielectric resonator antenna (DRA) and used as a sensing system for characterization of construction materials such as concrete. In this two-antenna setup, a DRA that acts as a receiving sensor-integrated antenna is embedded inside concrete and another external DRA (placed in free space) transmits wireless power to the embedded antenna. Both antennas are fed by X-band (8.2-12.4 GHz) open ended waveguide antennas (OEWAs). Transmission coefficients, reflection coefficients and electric-field distributions of these setups are investigated in the frequency range from 8 to 15 GHz. These investigations are performed with relatively long and short DRAs, and with OEWAs (without DRAs). In addition, sensitivity of the two-antenna sensing system to changes in values of the dielectric constants and loss tangent of concrete with the three antennas are analyzed. It is shown that the two-antenna sensing system with the long DRA and OEWA are more sensitive to the changes of both the loss tangent and dielectric constant of concrete than with the short DRA. However, the short DRA had a better performance with a magnitude of transmission coefficient that is significantly higher than those of the long DRA and the OEWA.