Electromagnetic ground-wave field of vertical antennas for communication at 1 to 30 MHz

Radio communication over the spherical surface of the Earth and sea makes use of vertical antennas in the frequency range from 1 to 30 MHz. For distances that extend beyond the approximation of a planar Earth, use must be made of the ground-wave. Following a description of antennas used on shipboard, their radiated fields are analyzed in the planar- and spherical-Earth regions. The latter involves new formulas for the field of vertical dipoles over the spherical surface of the sea.