Research On Key Technologies Of Magnetic Near Field Coupling Wireless Communication

In modern defense equipments and industrial applications,there is an increasing demand for information transmission in complex environments such as soil,water,human body and metal.Conventional radio communication technologies that use high-frequency electromagnetic waves for communications,signal energy is rapidly attenuated when propagating in medium such as soil or water,due to the characteristics of electromagnetic waves.Magnetic near-field coupled communication uses alternating magnetic field as the communication medium.In these media,the attenuation is much smaller than that of electromagnetic waves,which can effectively transmit signals in special environments such as soil,water,human body and even metal.Magnetic near-field coupled communication has become a research hotspot in the field of wireless communication with its above advantages.In this paper,the key technologies of magnetic near-field coupled wireless communication are deeply studied.The main research contents include:(1)The principle of signal transmission in magnetic near-field coupled wireless communication system is studied.The circuit model of the magnetic near-field coupled wireless communication system and the antenna coupling model are established and analyzed.The energy and efficiency of signal energy transmission in communication system are calculated,and the expression of signal energy transfer efficiency and maximum power when the system works under resonance condition is obtained.When the receiving antenna and the transmitting antenna communicate with each other at any relative position,The expression of mutual inductance between two antennas;for the typical metal machine architecture,the antenna near-field analysis in the metal environment is analyzed with the established antenna model,and the simulation is performed by software.(2)Aiming at the problem that the antenna angle of the traditional magnetic near-field coupled wireless communication system is not adaptable,an array type transmitting antenna is proposed.Firstly,the MIMO communication system model is used to analyze the communication system of the multi-transmitting antenna,and the influence of the phase and amplitude of the excitation voltage of each transmitting antenna on the coupling current of the receiving antenna is obtained.It is determined that the three types of transmitting antennas are arranged in an overlapping arrangement to form an array type transmitting antenna,and the genetic algorithm is used to determine the state of any receiving antenna.The phase and amplitude of the excitation voltage of the array transmitting antenna are the optimal combination of the system signal energy transmission efficiency.The software is used to simulate the near field of the transmitting antenna magnetic field to observe the change of the magnetic field strength direction.(3)Designing a magnetic near field wireless communication system experimental device.It is determined that the system adopts 2ASK modulation method,and the envelope detection circuit,signal conditioning and receiver load modulation circuit are designed.The physical system is fabricated and the signal transmission from the transmitter to the receiver at a distance of 1.2 meters and the signal transmission from the receiver to the transmitter at a distance of 0.2 meters are realized to achieve stable operation of the system...