An angle sensor based on a sector ring patch antenna for bolt loosening detection

Abstract This paper presents an angle sensor based on a sector ring patch antenna (SRPA) for loose bolt detection. The sensor is comprised of two parts, a ring substrate sandwiched between a ground plane and a sector ring radiation patch, and a sector ring substrate covered by a radiation patch. The two radiation patches are partially overlapped and the overlapped areas are in contact allowing the electric current to flow within the combined radiation patch. The resonant cavity theory is adopted to explain the relationship between the frequency shift and the overlapped angle. The Ansoft high frequency structure simulator software is used to simulate SRPA, and the dimensional parameters of the antenna are optimized to make the antenna perform better. For verification, two sets of SRPAs are fabricated and tested.