Groundwave Propagation Across Semi‐Infinite Strips and Islands on a Flat Earth

An electromagnetic groundwave propagating along the surface of the earth will be partially transmitted and partially reflected at an abrupt electrical discontinuity such as a coastline, lake, island, peninsula, river, certain types of mineral deposits, etc. The theoretical work of Wait is extended to yield a solution which can be applied to semi‐infinite or finite ground plane inhomogeneities of arbitrary shape. Calculations were made for two special cases: perpendicular propagation near a semiinfinite strip (e.g., a peninsula), and near a small rectangular island. The theoretical solution was experimentally verified to a good order of accuracy through the use of microwave‐frequency (4.3 Gc/s) laboratory models on which both amplitude and phase measurements were made. In these models, water was used to simulate imperfectly conducting media, while aluminum plates simulated perfectly conducting media. It is shown that the position of a semiinfinite strip or island transverse to the direction of propagation has considerable influence on the phase of the transmitted signal.