Transmission characteristic of electromagnetic wave between the ground and the air

When an electromagnetic wave comes into the ground from the air, it drops vertically from an incident point. Vice versa, an electromagnetic wave directs 45° from an incident point when it transmits into the air from the ground. The direction of transmission from the ground to the air has an useful meaning in that a sort of cavity phenomenon occurs in the area of just right over the source in the ground due to its obliqueness. This means that the effect of electromagnetic field decreases in that area. When an interference to another source in the air is analyzed, this phenomenon is worthwhile to be considered.