Research on the design method of horn antenna for monitoring cracks in metal structures

In structural health monitoring, patch antenna sensors are frequently employed. Yet, the adaptability between the transmitter and the sensor often remains overlooked in current wireless monitoring paradigms, engendering challenges in real-world applications. This study introduces a design methodology that utilizes horn antennas as a wireless excitation source, recognized for their superior characteristics. Concurrently, the metal ground plate of the patch antenna sensor serves as the signal-reflecting entity. The design aims to address the aforementioned adaptability challenges in wireless monitoring of metal structure cracks. Results demonstrate a pronounced linear correlation between the resonance frequency alteration of the horn antenna reading sensor and the variation in metal structure crack length. Notably, a crack detection sensitivity of -100 MHz/mm is observed as crack lengths range from 1.5 mm to 4.5 mm. Detection sensitivity, however, diminishes with increasing wireless monitoring distance. Nevertheless, a compelling linear association between resonance frequency variation and crack length remains evident. Given this persisting linear relationship between resonance frequency deviation and crack growth, it is imperative that wireless monitoring distances be strategically determined in accordance with crack detection sensitivity for engineering implementations.