Mechanical Deformation Detection of Building Structures Using Microstrip Patch Antennas as Sensors

A miniaturized quarter-wavelength microstrip patch antenna is developed to monitor the mechanical deformation of building structures. In order to minimize the physical dimension as well as improve the sensitivity of resonant frequency of the patch antenna, via holes are added to the antenna and the operational resonant frequency of the antenna is designed to be 2.4 GHz. Practical measurement for the resonant frequency is implemented to figure out the relationship between mechanical deformation and resonant frequency. Additional tensile tests are employed by increasing strain increments per loading step so that a larger shift caused by a larger deformation can be reached. It is revealed that the transmission efficiency of mechanical deformation is about 70% and the proposed antenna can sensitively monitor the mechanical deformation of building structures. Furthermore, different substrates in the antenna are investigated and the measurement results show that the RT5870 substrate has much better transmission efficiency than FR4 substrate. The proposed different antennas are designed to meet the specific needs of practical applications.