Encapsulated UHF antenna for early and long-term concrete monitoring

Abstract

This paper introduces a novel encapsulated 3D-printed UHF antenna system for early-stage and long-term concrete monitoring. Our goal is to leverage the capacities of additive manufacturing techniques to enhance antenna performance. We design and implement an encapsulated biconical geometry to mitigate medium losses due to being placed within concrete, to improve radiative efficiency, and to ensure stable antenna impedance. Various antenna prototypes were designed, optimized, fabricated, and characterized via laboratory and mortar sample measurements. We succeeded in integrating our novel system with existing temperature and humidity sensors, and interfaced it with an automatic data acquisition system for continuous concrete monitoring. Comparison with previous acquisition systems was performed. Herein, we present the design process, laboratory characterization, and field testing, including three case studies. Significant efforts were made to miniaturize the antenna while maintaining performance. Full system integration is demonstrated. Measurements were taken from antennas buried at depths of up to 30 cm; they showed good performance from an early start and up to long-term operation. These promising results confirm that improved antenna design and proper encapsulation can enhance system performance, especially in challenging and dynamic environments such as concrete.