An off-center fed patch antenna with overlapping sub-patch for simultaneous crack and temperature sensing

Abstract

This paper presents an off-center fed patch antenna for simultaneous crack and temperature sensing. The antenna sensor consists of an off-center fed underlying patch and an overlapping sub-patch. The bottom copper sheet of the sub-patch is tightly attached to the underlying radiation patch allowing the electric current to flow through the integrated patch. The off-center feeding can activate the resonant modes in both transverse and longitudinal directions. The transverse resonant frequencies of the combined patch are utilized for temperature sensing. Therefore, the crack width sensed by the longitudinal frequency shift can be adjusted, eliminating the temperature effect. In addition, this unstressed structure of the combined patch can avoid the issues of incomplete strain transfer ratio and the insufficient bonding strength of a monolithic antenna. The authors developed theoretical relationships between the antenna resonant frequencies, the temperature, and the crack width. They also developed simulations of the off-center fed patch antenna sensor as well as a series of experimental tests to demonstrate the feasibility of the proposed sensor for simultaneous crack and temperature sensing.

Bidirectional large strain monitoring using a novel graphene film-based patch antenna sensor

“…In addition, as a carbon material, graphene has good chemical stability and adaptability to complex environments compared with metal materials [40]. Based on the four-probe method [41], the graphene film showed a high conductivity of 1.1 × 10 6 S m −1 . In addition, the PET film used for the substrate of the patch antenna is provided by South China Xiangcheng Technology, with a thickness of 0.35 mm, a dielectric constant of 3, and a dielectric loss of 0.06.…”

“…Additionally, for antenna sensors, temperature also affects the dielectric constant of the substrate of antenna. Li et al [41] found that there is a linear relationship between temperature and the resonant frequency of the antenna through theoretical analysis and experiments. Therefore, temperature experiments were conducted to investigate the effect of temperature on the resonant frequency of the proposed graphene antenna sensor.…”

Simultaneous crack and temperature sensing with passive patch antenna

“…This multiple physical variable monitoring sensor enabled dielectric constant and temperature sensing by a single antenna sensor, eliminating the need for additional temperature sensors. Li et al 39 proposed a dual-resonant patch antenna to detect the crack width and temperature changes, which is the preliminary work of this article. The antenna sensor has been proved to be feasible in laboratory environment.…”