HF Ground Wave Propagation over Mixed Land, Sea, And Sea-Ice Paths

Ground wave propagation is analyzed for a two-section path on a spherical earth. Each section can be a two-layer medium which is characterized by a surface impedance. Specific calculations for a land-to-sea path indicate that the well-known recovery effect in amplitude and phase is more extreme at higher frequencies but is reduced for elevated observer heights. Calculations for a sea-to-sea ice path indicate a brief recovery because of the excitation of the trapped surface wave over sea ice. At greater distances from the boundary, the field may be seriously degraded due to the sea ice.