Radiation and reception with buried and submerged antennas

The paper is intended as a link between the abstruse boundary value problem solutions and the systems engineer. A brief bibliographic review of the boundary problem is given, followed by a discussion of the several approximate solutions and their regions of validity. The propagation path, for almost all practical applications, consists of an evanescent wave from the transmitting antenna to the surface where a conventional Norton surface wave is excited. Part of the wave energy leaks into the lossy medium, thus reaching the receiving antenna. Merit factors are given for three types of antennas: loops and dipoles in insulating radomes, and an insulated long wire with end electrodes. A particularly useful merit factor, relative gain, which relates vertically polarized power per unit solid angle over the surface to total input power, is defined. The long wire is shown to be appreciably superior to loops or dipoles. Among the latter two, superiority depends on the relative sizes of radome, skin depth and wavelength. A simplified physical model is presented wherein the fields of the long wire are derived from a vertical quadripole of conduction current. Due to the low mutual impedance between antennas in lossy media, some array gain can be realized without concomitant beam sharpening.