Dual-band piezoelectric artificial structure for very low frequency mechanical antenna

Very low frequency (VLF) (3–30 kHz) communication systems are widely used in remote and underwater scenarios due to the low propagation loss. However, the antenna size and complex impedance matching network restrict the development of portable VLF transmitters. Here, we demonstrate a compact dual-band piezoelectric artificial structure for very low frequency mechanical antenna for the enhancement of electromagnetic radiation. The mechanical antenna consisted of piezoelectric ceramic rings operating at 25.61 kHz and 35.79 kHz. A VLF communication system is designed to verify the radiation efficiency of the proposed mechanical antenna. At 25.61 kHz and 35.79 kHz, the measured magnetic field intensity can reach 0.118 nT and 0.084 nT at a distance of 5.4 m. Due to the piezoelectric artificial structure, the radiation enhancement of the proposed antenna has been experimentally demonstrated within the range of 20–40 kHz. This mechanical antenna has great potential in applications of portable, low-cost, and high-performance VLF wireless communication devices.Graphical abstract A dual-band very low frequency mechanical antenna with the piezoelectric artificial structure is proposed. The antenna consisting of varisized piezoelectric ceramic rings can work at 25.61 kHz and 35.79 kHz. With the piezoelectric artificial structure, operating frequency bands of the proposed VLF mechanical antenna are expanded. Measurements demonstrate the feasibility of the proposed mechanical antenna in VLF communication.