Complementary open loop-curved surface coupling sensor for measuring moisture of lubricating oil

The invention provides a complementary open-loop-curved-surface coupling sensor for measuring moisture of lubricating oil. The complementary open-loop-curved-surface coupling sensor comprises a conductor belt, a dielectric substrate and a grounding plate, wherein the dielectric substrate and the grounding plate are stacked in sequence; a circular ring structure and a square ring structure are etched on one end face of the dielectric substrate; the circular ring structure is arranged in the square ring structure; the conductor belt transversely penetrates through the circular ring structure and the square ring structure; the conductor belt is used for sending a microwave signal to the dielectric substrate and collecting an echo signal; the echo signal is used for calculating and determining the moisture content in the to-be-detected lubricating oil; the circular ring structure and the square ring structure are used for gathering electric fields. According to the invention, the detection of the moisture content