Self-Calibrating Circuit for Phase Correction in Magnetoelectric Antenna Arrays

Magnetoelectric (ME) antennas driven by acoustic excitation achieve electromagnetic radiation with high energy conversion efficiency and compact dimensions down to the centimeter scale. This makes them highly promising for portable very low frequency communication applications. However, inevitable fabrication tolerances and other variations among ME antenna elements lead to phase inconsistencies, resulting in destructive interference of the array quasi-static near field and severely limiting practical performance. To address this issue, this letter presents a closed-loop phase self-calibration system based on a field-programmable gate array (FPGA). Operating at a center frequency of 13.6 kHz, the system performs phase detection and automatic compensation in a single closed loop at startup, ensuring all antenna elements are initially phase-aligned. Experimental results demonstrate that, of the four ME antenna elements, the initial phase difference between ME1 and ME4 is close to 180°. After calibration, the magnetic flux density at 1 m is 7.9 times that of the uncalibrated case, and the magnetic flux density of the uncalibrated four-element array is lower than that of a single antenna. This study provides an effective solution for controlling the phase consistency of ME antenna arrays.