基于驻极体材料的机械天线式低频/甚低频通信磁场传播模型

Magnetic field propagation model of low frequency/very low communication based on mechanical antenna of electret

低频/甚低频电磁波的频率极低,趋肤深度较深,可以以很小的损耗穿透海水和地下来进行通信.传统的低频发射天线存在尺寸和功耗较大的问题,本文采用驻极体材料设计了一种机械天线式低频/甚低频发射天线结构.利用激励装置驱动驻极体所带极化电荷进行机械运动,从而产生交变的电磁场,并激发出电磁波携带能量和信息,在一定的媒质中传播,以实现电磁波的高效辐射,颠覆了传统低频/甚低频发信系统中天线尺寸需与辐射信号波长相比拟的约束.基于该结构,本文建立了磁场传播的解析模型,并据此研究了天线尺寸、形状等相关参数对天线性能的影响.给出了天线所产生场强随几何参数如半径、高度等的变化规律,同时对比了两种不同磁场模型仿真计算的结果,阐述了在实际情况中需要根据天线尺寸和传播距离等条件来选择适合的模型.研究工作对于指导机械天线设计和优化天线结构具有重要意义.

Because of its stable propagation characteristics and small attenuation in the medium,low-frequency(LF)electromagnetic wave can penetrate into the sea and underground with small loss.Although its transmission bandwidth is narrow,which limits its application range,it has irreplaceable wide applications in long-distance navigation,communication and frequency release,especially in underwater communication.Therefore,the study of low frequency/very low frequency(LF/VLF)propagation is of great theoretical and military value.In the LF/VLF communication systems,the transmitting antenna is an extremely important part,and its performance has an important influence on the whole system.However,the wavelength of the LF electromagnetic wave is very long.In order to obtain the ideal radiation effect,the traditional method needs a huge transmitting antenna system,which is too large in size and power consumption.Therefore,it will be a disruptive innovation in the field to realize a technology that can significantly reduce the size the existing LF/VLF information network communication system.In view of this,in this paper we propose a kind of LF/VLF signal transmitting antenna in which an excitation device is used to drive the polarization charge of the electret to move mechanically.By accelerating the charge to form a conductive alternating electromagnetic field which can generate and radiate electromagnetic wave,under the excitation of the wave source,it carries the energy and information in the form of energy flow and propagates in a certain medium.Then,through using the magnetic field receiving system to measure the magnetic field vector in the electromagnetic wave,the effective LF/VLF signal can be obtained,thus achieving the high electromagnetic wave effective radiation which overturns the restriction that the antenna size needs to be comparable to the wave length of the radiation signal in the traditional LF navigation communication system.At the same time,an analytical model of magnetic field propagation is established based on this structure,and the influence of antenna size,shape and other relevant parameters on the performance of antenna communication are studied as well.In order to reduce the loss of accuracy and improve the calculation speed,it is necessary to choose the correct analytical model and the appropriate parameters of magnetic field generated by the mechanical antenna according to the actual situation.The research work is of great significance for designing and optimizing mechanical antennas.