The ancient and modern history of EM ground-wave propagation

Lateral and transverse shifts in reflected dipole radiation

“…The Brewster angle is a zero of the in-plane reflection coefficient; but, on a different Riemann sheet, q B also corresponds to a pole, representing a surface wave in certain cases where n is complex, for example, when one medium is conducting. The surface wave does not contribute directly to the reflected wave-unsurprising because the reflection coefficient is zero-but was nevertheless the subject of controversy for many years (Kahan & Eckart 1949, 1950Wait 1998). The reason for a strong lateral shift at q B is the denominator |S| in the normalization of the unit vector in equation (1.1): away from q B , this is dominated by the geometrical wave, which vanishes at q B itself.…”

Towards a Better Excitation of the Surface Wave

“…This wave, when sea and air are considered at HF frequencies, has a very slow decaying rate along the sea surface and a very fast decaying one in the direction normal to the interface: this peculiarity made the radio-wave community at the beginning of the 20th century believe that transoceanic communications were possible thanks to Zenneck Wave [5]. However, they were wrong: an error sign in Sommerfeld's paper was the cause of years of misunderstandings [4,6]. More recent studies provide the correct expressions of the field excited on the sea surface by a source placed in its vicinity [7], while the existence of a pure Zenneck wave is still discussed [8,9].…”

“…Since sea water at HF frequencies can be seen as a lossy conductor, surface wave is vertically polarized and vertical wire antennas, located close to the sea, are often used to excite it. Many studies, both theoretical and practical, have been led to determine the characteristics of the fields radiated by a wire antenna above a lossy conductor: we can cite seminal works by Zenneck, Sommerfeld, Norton, Burrows, Bremmer, Fock and Wait (for a complete bibliography on the subject, please refer to [4]). …”

Application of Media with Negative Refraction Index to Electromagnetic Imaging. Fundamental Aspects.

“…It was considered the propagation of an electromagnetic wave radiated by an elementary electric Hertz dipole located in the air (or vacuum) parallel to the boundary of a layer or, in a particular case, to the boundary of a half-space filled with a material with negative refractive index. It was applied a rigorous approach that dates back to Sommerfeld [Sommerfeld (1926), Wait (1998)]. The scientific discussion around the resolution of superlens has shown that there is some lack of understanding in the theory of diffraction which has a fundamental significance.…”