A generalized solution of the problem of electromagnetic wave propagation in a linear dielectric layer indicates that variation of a phase of an incident wave varies the height locations of the nodes and antinodes of the standing wave under the reflection point. The depth of electromagnetic wave penetration above the reflection point additionally depends on the initial phase of the incident wave. Thus there is an opportunity to control wave penetration above a reflection point. ¿ 2001 American Geophysical Union