A method for omni-directional radiating SLF radio signal based on grounded antenna

In order to solving the problem of extremely low efficiency for radiating SLF signal, in this paper we study a method of antenna designing based on grounded antenna and analysis the direction characteristic of the grounded antenna. Using this design method, the SLF antenna has the shortest size and the highest efficiency. Because the grounded antenna has the direction characteristics, the reliability of underwater mobile platform communication that use one grounded antenna is not consistent in different waters. Therefore, in this paper a method of omni-directional radiating SLF signal is presented. According to this method, the SLF antenna array is built with two orthogonal grounded antennas. By controlling the phase difference of two orthogonal antennas´ input current, we can make the synthetic electric field strength that the antenna array radiates equal and uniformity in all horizontal direction, so we can realize the SLF signal to omni-directional and equal power radiating. This method is simple and easy to apply to underwater SLF communication, but the control of current phase difference must be accurately. Using this method we can significantly improve the reliability of SLF communication. It is very important to underwater mobile platform communication and underwater communication.