Research On Low Frequency Mechanical Antenna Based On Rotating Permanent Magnet

Low-frequency electromagnetic waves have super strong anti-interference ability and penetration performance,and can be widely used in fields such as underwater submarine communication,underground detection and early warning,and space long-distance transmission.The structural size of the traditional antenna system that emits low-frequency electromagnetic waves is limited by frequency,making its efficiency extremely low and unable to meet the actual needs.The novel mechanical antenna directly converts mechanical energy into electromagnetic energy,which breaks through the limitation of antenna size on frequency and overcomes this problem well.However,the current research has certain defects and deficiencies in the structural forms and electromagnetic performance improvement of mechanical antennas.Therefore,this paper analyzes and designs the radiating element,array structure and modulation method of the mechanical antenna,and conducts prototype development and experimental verification.The main works can be described as follows:1.Analysis of electromagnetic performance of mechanical antenna and its array based on rotating permanent magnet Firstly,based on the radiation mechanism of the mechanical antenna,the Nd Fe B with the best performance was chosen as the radiation unit.Next,the electromagnetic performance of the radiation unit model of the rotating permanent magnet mechanical antenna,such as time domain characteristics,frequency domain characteristics,magnetic field distribution,and the influence of the parameters of the radiation unit on the electromagnetic performance,are analyzed.Finally,in order to improve the near-field magnetic field characteristics of mechanical antennas,binary antenna array,rotating linear Halbach array,and rotating square array are proposed.Through simulation calculation,the basic electromagnetic performance of the three array structures is determined.The results show that the proposed rotating square array structure has the strongest near-field magnetic field under the premise of ensuring the same magnet volume,which is 27.4% higher than the magnetic field of a single rotating permanent magnet.2.Mechanical antenna prototype production and basic performance verification.In order to verify the basic electromagnetic characteristics of the proposed mechanical antenna array structure,prototypes of the transmitting antenna and receiving antenna of the entire test system were made.Then,A test system for measuring the near-field of the mechanical antenna was developed.Finally,the performance of the mechanical antenna was experimentally verified by this near-field test system.Experimental results show that the designed mechanical antenna array can emit time-varying electromagnetic wave signals,and its performance tend to be consistent with the results of simulation analysis.The correctness of the proposed array antenna model is verified.3.Design of mechanical antenna based on signal modulation.In order to further optimize the performance of the mechanical antenna,firstly,according to the basic principle of the communication signal frequency modulation method and the radiation mechanism of the mechanical antenna,the frequency modulation method of the mechanical antenna is proposed,and the changes before and after the communication signal modulation are simulated and analyzed.Then,an amplitude modulation method based on electromagnetic resistance modulation is proposed.By analyzing the mechanism of this amplitude modulation method,the factors that affect the modulation effect are determined,and the corresponding amplitude modulation device is designed.Finally,the designed amplitude modulation device has been prototyped and verified by experiments.On the one hand,the experimental test results verify the correctness of the optimization model,and on the other hand,it also verifies the effectiveness of the amplitude modulation device designed in this paper.