Mode-expansion method for predicting radar signature above rough ocean surfaces at low-grazing angle

The mode-expansion method (MEM) is introduced to calculate the electromagnetic (EM) waves scattered by 2D rough water surfaces at low-grazing angles. The electric field integral equation (EFIE) is used in defining the problem and is simplified by using the impedance boundary condition (IBC). The surface currents are expressed as the sum of modes expanded as a Fourier series with the incident wave as the dominant mode. It is shown that, by the MEM and for the geometry with transmitting and receiving waves at low-grazing angles, very few modes are needed in solving the forward scattering field with reasonable accuracy.