A patch-antenna-based smart aggregate for passive strain sensing in concrete

Abstract

This paper presents an innovative smart aggregate based on passive patch antenna. The designed unstressed patch antenna components which can move relatively serves as a sensing unit, and the sensing unit can be embedded in concrete to form smart aggregates for strain sensing after encapsulation. The study investigates the influence of different encapsulation materials and external environments on the electromagnetic parameters of the patch antenna sensing unit within the smart aggregate. Furthermore, it establishes the theoretical relationship between the resonant frequency of the sensing unit and the deformation of concrete. When using shielding material to encapsulate the patch antenna, it can avoid the influence of external dielectric environment variation; when using non-shielding materials to encapsulate the patch antenna, external environmental sensing can be achieved. Simulations and experimental tests were used to study the characteristics of two different encapsulation methods. Two patch-antenna-based smart aggregates with different dielectric substrates, Rogers RT5880 and Rogers RO3010, were fabricated, which can be embedded inside the concrete and realize the passive sensing of the internal strain of the concrete. The fabricated smart aggregates no longer require continuous power supply, thus having better applicability. Experimental tests were undertaken to demonstrate the viability of the proposed patch-antenna-based smart aggregate. The sensing sensitivities of the proposed smart aggregates based on patch antennas with dielectric substrates Rogers RO3010 and Rogers RT5880 were 1.219 MHz/100 με and 0.598 MHz/100 με, respectively.