Experimental test of patch antenna sensor for simultaneous crack and temperature sensing

Abstract

Abstract. This paper presents a patch antenna sensor for simultaneous crack and temperature sensing, and its actual performance is tested. The patch antenna sensor consists of an off-center fed underlying patch and an overlapping sub-patch, which is tightly attached to the underlying patch and allowing the electric current to flow through the integrated patch. The off-center feeding of the patch antenna can activate the resonant modes in both transverse and longitudinal directions. The resonant frequency shift in transverse direction is utilized for temperature sensing, and the crack width can be sensed by the longitudinal resonant frequency shift. Furthermore, this unstressed structure of the patch antenna sensor can avoid the problems of incomplete strain transfer ratio and the insufficient bonding strength. In this paper, the theoretical relationships between the antenna resonant frequencies, the environment temperature, and the crack width were studied. Experimental tests were also conducted, the off-center fed patch antenna sensor was fabricated and several days of continuous monitoring were performed to test the sensing performance of the patch antenna sensor. The experimental results demonstrate the feasibility of the proposed patch antenna sensor for simultaneous crack and temperature sensing.