Research on air-sea cross-medium communication based on mechanical antenna

Abstract The high-conductivity conditions underwater create considerable difficulties for current high-frequency communication systems. Very Low Frequency (VLF) communication has become a viable solution due to its reduced radiation attenuation. However, traditional long-wave antennas require large sizes to operate at these frequencies, which makes them difficult to transport, install, and maintain. Mechanical antennas, on the other hand, generate electromagnetic radiation by using mechanical vibrations to induce the flipping of electric or magnetic dipoles within the material, overcoming the size and efficiency limitations of conventional long-wave antennas and enabling miniaturization. Current research on mechanical antennas primarily focuses on signal transmission in single media, such as air or water, while studies on cross-medium communication systems remain underdeveloped. In this study, a mechanical antenna made from magnetoelectric (ME) composite materials was used to investigate cross-medium communication performance in a practical communication system. The basic theory of mechanical antennas was first explained. An antenna suitable for the desired frequency was designed through simulation, verifying its equivalence to a magnetic dipole model. Based on electromagnetic wave transmission theory across air-water media, an electromagnetic field model for vertical magnetic dipole cross-medium transmission was established. Afterward, the mechanical antenna was fabricated. Relevant tests were conducted in an actual communication system. The results showed that the designed Metglas-PZT mechanical antenna, operating a resonant frequency of 14.1 kHz, achieved a communication rate of 200 bps and error-free text transmission over a total distance of 1 meter, including 0.7 meters in air and 0.3 meters underwater, using 2ASK modulation. These results confirm the feasibility of mechanical antennas for air-water cross-medium communication and provide important references for future research in underwater communication.