Field and Array Factor of a VLF Dipole Antenna Array Located in an Anisotropic Ionosphere

With the increasing importance of contemporary very low frequency (VLF: 3-30 kHz) space-borne transmission and propagation systems in applications such as underwater communications and navigation, it is important to study the radiation field of a space-borne VLF dipole antenna array in an anisotropic ionosphere. In this paper, the radiation field of a VLF dipole array in an anisotropic ionosphere is investigated. The effect of ionospheric parameters on the radiation field of a VLF dipole antenna as well as the variation law of the electric field of a VLF dipole array with different propagation angles are explored. Then, the effect of the number of array elements and spacing on the field distribution of an array is analyzed. The results show that the electric field strength gradually decreases with the increase of propagation distance and electron collision velocity. In addition, for the multiple-element array, the overall field strength increases when the spacing of the space-borne VLF dipole array is short. By studying the radiation field of a VLF dipole array and the effect of ionospheric parameters on the field distribution, it is beneficial to provide theoretical support for the radiation mechanism of the arrays involved in the actual space-borne transmitting and propagation systems.