A Directional Pattern Reconfigurable Low-Frequency Antenna Based on Permanent Magnet Array

Benefiting from the strong penetrative and anti-interference properties of low-frequency (LF, between 3 Hz and 300 kHz) electromagnetic (EM) waves, LF signals hold immense application potential in various fields including underwater communication, pipeline monitoring, and through-the-Earth communication. Among these applications, rotating permanent magnet antenna (RPMA) stands out due to its compact size, low-power consumption, high efficiency, and strong radiation intensity. Meanwhile, its omnidirectional characteristic leads the antenna with broad signal coverage. However, this omnidirectionality may lead to signal interference and increasing bit error rates when multiple RPMAs transmit signal simultaneously, which will reduce communication performance. Meanwhile, current researches mainly focus on enhancing RPMA’s radiation intensity with insufficient in-depth discussion on directionality. To meet the demand of directionality in different scenarios, this work proposes a directional pattern reconfigurable antenna based on RPMA array. The influence of factors such as the number of elements, spacing, distribution, and phase on the directional characteristics of the magnetic field intensity generated by RPMA arrays is comprehensively considered, and the antenna’s directivity can be enhanced 2.67 times. Through experimentation with a designed three-element RPMA array, this work demonstrates the reconfigurability of directional characteristics and validates the communication robustness. By simple positional adjustments and phase control, the directionality can be changed flexibly between omnidirectional and directional characteristics. This directional pattern reconfigurable antenna offers significant advantage in improving communication quality, which will pave the way for future advancements and applications of RPMA.