An approach for enhancing communication efficiency in the sphere-string mechanical antenna

Abstract The mechanical antennae generate electromagnetic radiation through mechanical motion, overcoming the size limitations of traditional low-frequency antennae and demonstrating great potential for underwater communication applications. In this study, the frequency modulation performance of the sphere-string mechanical antenna is investigated. Time–frequency analysis of the received signals is performed using the Superlet transform and Hilbert–Huang Transform, based on both simulation and experimental data. The minimum time interval for switching between resonance frequencies, while ensuring modal transition completeness, was determined by detecting the maximum frequency change rate. To enhance the information transmission capability of the array-based mechanical antenna, a Bagua encoding scheme was proposed based on the sphere-string mechanical antenna array. Furthermore, the relationship between structural parameters and resonant frequency is analysed, providing a theoretical foundation for future design optimization. This work offers both theoretical insights and experimental support for the engineering application of the sphere-string mechanical antenna.