Amplitude modulation method of super-low frequency mechanical antenna based on magnetic shielding technology

Abstract

Mechanical antenna is a new radiation mechanism that uses magnetic(polar) materials to radiate low-frequency signals, which is expected to solve the problems of large volume, high power consumption and low efficiency of existing low-frequency electrical antennas. In recent years, frequency modulation, which is widely used in the research of mechanical rotary transmitting antenna, has limitations in mechanical drive. This paper proposes a super-low frequency(30～300 Hz) mechanical antenna amplitude modulation method based on magnetic shielding technology, which separates radiation and modulation and performs them independently. The modulator controls the attenuation of the total field propagating outward through the states "open" and "closed" to realize amplitude modulation. Three-axis orthogonal coils are used to receive signals with different polarization directions. The characteristics of electromagnetic field generated by rotating permanent magnet are analyzed, the modulation is simulated, and an experimental prototype is built to verify the feasibility of the proposed method. The experimental results show that the information modulation does not need the permanent magnet to change the rotating speed frequently, thus overcoming the mechanical challenge faced by the frequency modulation of the rotary transmitting antenna.

Keywords

• super-low frequency
• mechanical antenna
• rotating permanent magnet
• amplitude modulation