Research on mechanism and key technology of mechanical antenna for a low-frequency transmission

Abstract

Unlike conventional electrically small antennas (ESAs) that rely on the electromagnetic wave excited by the oscillated current in a conductor, the mechanical antennas (MAs) use a novel low-frequency (LF) transmission technique that utilizes the mechanical motion of electric charge or magnetic to generate the electromagnetic wave directly. This transmission technique is a promising solution for overcoming the physical limit of ESAs, and solving the problems of a large volume, complicated facilities, low radiation efficiency, and large transmission loss of current LF transmission systems. Accordingly, it can improve the motility and flexibility of the LF communication, and thus has a wide prospect in the underwater and underground communication and navigation and location applications. First, the definition and research status of the MA are introduced. Next, the realization and physical model investigation of the MA are provided. Then, the distribution model and attenuation characteristic of the time-varying electromagnetic field in space are explained in detail. According to the comparison of different types, a general structure of the MA is proposed. The main challenges regarding the high-efficiency utilization are introduced, and the application mode and prospect are described. A rotatingmagnet based MA prototype composed of a NdFeB high-speed permanent magnetic servo electrical machine is developed using the proposed MA structure. The time-varying magnetic field characteristic of the prototype is preliminarily verified by the near-field measurement, as well as the possibility and effectiveness of the FSK modulation.