Reflection of Radio Waves from the Surface of the Earth

The reflection of an elliptically polarized electromagnetic wave from partially conducting and perfectly conducting surfaces is studied in detail. It is shown that in either case the interference of incident and reflected waves gives rise to a pseudo-stationary wave field above the surface of the reflector. This field is bodily propagated along the horizontal projection of the direction of the incoming wave with a velocity greater than that of light, i. e., c/sin α where α is the angle of incidence. The resultant field at any given point lies in a plane whose orientation varies with height. This fact is made the basis of experimental measurements. It is found that the 43-meter wave from WIZ, located at New Brunswick, N.J., holds its polarization and angle of incidence constant during morning hours at Ithaca, N.Y. The rapid fading that accompanies the signal is attributed to purely amplitude fluctuations. Observations on this station are analyzed, and it is shown on the basis of the above theory how it is possible to obtain the angle of incidence as well as complete information regarding the polarization of the incoming wave. Measurements on almost all other stations ranging from 25- to 50-meters wavelength show highly erratic conditions.