Electromagnetic propagation in four-layered media due to a vertical electric dipole : a clarification

This communication presents a quasi-analytical method for predicting the electromagnetic propagation in four-layered media due to a vertical electric dipole. The method includes the components known as the direct, ideal reflected, lateral, and trapped surface waves. Previous literature, studying less complex geometries, is extensively reviewed and found to be incomplete and inaccurate in a number of places. These deficiencies are highlighted and the methodology is presented with enough detail to allow repetition of the results. Results are shown which approximate the scenario of a leaking water-pipe, buried in the shallow sub-surface. It is shown that the trapped surface wave does not dominate in this scenario. Furthermore, it is shown that the trapped surface wave magnitude is reduced when conductivity of the fourth layer is reduced, or when the third layer thickness is increased; these results fit the qualitative expectation based on previous results.