On some wide band radar propagation effects over sea

Propagation over sea is frequently affected by anomalies like ducting. The paper presents a description of a propagation model for wide band modulation radar, based on the parabolic approximation of the Maxwell equations. The model synthesizes wide band effects from a number of narrow band results. This model is then applied to compute the effects on the forward propagation factor for wide band signals and narrow band signals in scenarios with ducting. The result is that the overall structure of the narrow band propagation factor is close to the wide band propagation factor except for some deep fades. Using the model, also the changes in the pulse shape of wide band radar signals due to the dispersive character of the propagation are computed. It is concluded that dispersion due to wide band propagation in the computed scenarios with a 22% bandwidth is not really significant and will not impose severe limits on the capabilities of wide band radar