Long-wave electromagnetic waves have significant potential applications in deep-sea communication and detection. To address the challenges associated with the construction of high-power long-wave transmission systems, including large antenna dimensions, complex engineering implementation, and high input power requirements, this study explores the utilization of existing infrastructure resources to develop a novel transmission system.

First, the similarities and differences between the horizontal antennas and overhead power lines in power grids are analyzed, demonstrating that overhead power lines can serve as horizontal antennas. Subsequently, a transmitting system scheme consisting of an AC overhead power line for power delivery, a transmission module, a coupling module, and a separation module is proposed, and the design methods for each module are presented.

A 300 kW long-wave transmission system operating at 210 Hz based on a 110 kV AC power line is simulated to demonstrate that the AC power lines can simultaneously transmit electric power and long-wave signals through coupling and separation modules. Electromagnetic simulation results indicate that the proposed system can generate a magnetic field on the order of femtotesla at a distance of 350 km and a depth of 100 m below the sea surface. Furthermore, experimental simulations were performed on a long-wave transmission system with a transmission power of 20 W, validating the communication capability of the proposed method.

The in-service AC power lines can provide strong support for the development of flexible long-wave transmission systems for both military and civilian applications.