Radiation Principle and Spatial Direct Modulation Method of a Low Frequency Antenna Based on Rotating Permanent Magnet

The theory of mechanical antenna is still in its infancy at present, and its radiation mechanism, field distribution, modulation methods and other basic theories need to be explored and improved. The radiation mechanism of a rotating-magnet based mechanical antenna (RMBMA) is explored. An equivalent radiation model of the mechanical antenna is established. The field formula of mechanical antenna is derived using this model and rotation matrix. The spatial direct modulation method of mechanical antenna is also investigated. Two prototype antennas are fabricated using DC/AC servo motors and NdFeB magnets, and experiments are carried out to verify the correctness of the derivation and analysis. The measured and simulated results are in consistent with each other. By precisely controlling the moving parameters of an AC servo motor, signal of binary amplitude shift keying (BASK) is generated, and the original code sequence is recovered by demodulation.