Effects of ducting on radar operation in the Persian Gulf

During the 1988 Iran/Iraq conflict, long-range radars located on ships were used for surveillance of the Persian Gulf. During periods of ducting, their surveillance of the horizon indicated large increases in sea clutter, which occurred far past the normal line-of-sight horizon and at an amplitude level that exceeded the predicted propagation conditions. An explanation based on ray theory is provided for the excess sea clutter. It is shown that an increase in the amount of radar signal scattered by the ocean waves is due to the existence of an evaporation duct and that the propagation range of the sea clutter is increased due to the presence of a surface-based duct. This explanation and certain aspects of the measured data are used to predict the expected sea clutter in a ducting environment and to confirm the theory.<>