Assessment of the shadow zone caused by the atmospheric duct for the shipboard radar and the measures of filling the shadow zone

The atmospheric duct is an abnormal refraction in the atmosphere of the troposphere; it can change the normal propagation characteristics of the electromagnetic wave, so that the propagation energy of the electromagnetic wave is redistributed and the over-the-horizon detection of the ship-borne radar can be achieved on sea, at the same time the shadow zone of the shipboard radar can be caused by the atmospheric duct. In this paper, by using “the detection probability distribution method of the radar electromagnetic wave”, we evaluate the distribution of the shadow zone caused by the atmospheric duct. Furthermore, according to the different frequency radar, we analyze the distribution of the shadow zone for the s-band and c-band and x-band radar under the environment of the different atmospheric duct respectively, and the measures of filling the shadow zone are given for the shipboard radar.