Optimizing PLA 3D printed infill designs for maximum strength and minimal interference in harmonic transponders

Harmonic transponders are used to measure soil moisture and temperature, aiding post-burn land assessments and the prediction of hazards such as landslides and flooding. However, packaging materials can impact their signal performance. This study investigates how different 3D-printed PLA infill patterns affect signal return and structural integrity.Using a Bambu Lab P1S printer, square and triangular infills at 40% density were tested across multiple packaging configurations at 890 MHz and 1.2 GHz. Results showed that square and triangular patterns offered comparable signal transmission with minimal disruption, despite undergoing plastic deformation. Corrugated infill caused more signal interference but fractured in a brittle manner, offering better transponder protection. These findings highlight how infill design influences both signal reliability and mechanical behavior—factors that directly affect the accuracy of environmental data collected by the transponders.