An Efficient Dynamic Seawater Antenna Based on Choke Magnetic Ring

To address the dual requirements of antenna miniaturization and medium-to-long range communication for marine Unmanned Surface Vehicles (USVs), this letter proposes a dynamic seawater antenna with a 20 mm radius and 1.4 m height, capable of cross-band operation in both High-Frequency (HF) and Ultra-High-Frequency (UHF) bands. To improve the radiation efficiency of the seawater antenna in this configuration, a choke magnetic ring is introduced at the antenna's base to suppress current leakage and improve radiation efficiency. This letter presents a detailed analysis of the choke ring's operational principle, along with selection criteria for its dimensions and material. The effectiveness of the choke ring is validated through simulations conducted with FEKO software and practical field experiments at the seaside. Simulation results show that the radiation efficiency can be improved to a level close to that of a same-size static seawater antenna, while field experiments demonstrate an increase in the Signal to Noise Ratio (SNR) of up to 8 dB at certain frequency points and the Figure of Merit (FOM) is calculated to be 76.95 1/m at resonant frequency point.