The recent space technology is capable to design a spaceborne VLF/ELFtransmitter and antenna for the communications to submarines, in this.case, the antenna is a vertical wire in the F-layer of the ionosphere at a height of 400km. Forsimplicity, the antenna is idealized as a dipole, the ionosphere is idealized as ahomogeneous anisotropic plasma with sharp boundaries, the VLF magnetic fieldon the sea surface is analyzed and calculated.