Mechanical Magnetic Field Generator for Communication in the ULF Range
Electromagnetic (EM) fields at radio frequencies (RF) cannot penetrate deep into media with high conductivity such as sea water, wet soil, etc. However, moving to the ultralow frequency (ULF) range (300 Hz-3 kHz) allows a considerable range of communication due to the decreased medium loss at low frequencies and a possibility to use the penetrating near field. Magnetically coupled coils are commonly used for near-field magneto-inductive (MI) communication. Alternatively, it is possible to create ULF magnetic fields of sufficient amplitude by rotating permanent magnets. In this work, a ULF magnetic field generator has been created using a rotating permanent magnet. It has been shown that the proposed field generator outperforms a conventional coil source (23 dB of field strength for the same volume and dissipated power that is 0.35 W), which can be a considerable advantage for low size, weight, and power applications. A method to produce amplitude shift keying (ASK) modulation signals using a modulation coil was proposed and analyzed. It was demonstrated that the inductance of the modulation coil is not critical for achieving acceptable modulation ratios, which opens a possibility for a compact ASK generator design. A simple circuit model and analytical formula for modulation efficiency of the generator were proposed and validated by measurement.
H. Rezaei et al., "Mechanical Magnetic Field Generator for Communication in the ULF Range," IEEE Transactions on Antennas and Propagation, vol. 68, no. 3, pp. 2332 - 2339, Institute of Electrical and Electronics Engineers (IEEE), Mar 2020.
The definitive version is available at https://doi.org/10.1109/TAP.2019.2955069
Electrical and Computer Engineering
Mechanical and Aerospace Engineering
Keywords and Phrases
Magneto inductive (MI) communication; near field; rotating permanent magnet
International Standard Serial Number (ISSN)
Article - Journal
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01 Mar 2020