A comparison of propagation over rough sea surfaces using MOM and PWE methods

Microwave propagation over rough seas plays an important role in maritime communication and surveillance applications. For propagation between low altitude antennas, the prediction of the electromagnetic fields is complicated by a number of effects including: 1) non-flat rough sea surfaces caused by wind waves and swell, 2) shadowing or blockage of direct-path due to wave crests, 3) finite conductivity surface boundary conditions, 4) surface waves (for vertical polarization), and 5) boundary effects which lead to non-planar wave fields near the air-sea interface. Traditional methods for modeling RF path loss or propagation factor using simple 2-ray geometrical optics models, or even spherical wave models, fail to correctly predict the near surface EM fields. More exact propagation techniques such as integral equation or parabolic wave equation (PWE) methods could be employed to predict the fields, but the veracity of PWE for near surface predictions has often been questioned.