| In the marine atmospheric environment,the atmospheric duct will have an important impact on the marine radar detection,navigation and other systems.The study of the propagation characteristics in the marine atmospheric duct environment can provide a reference for the design and efficiency evaluation of relevant weapons and equipment.In the thesis,the propagation model of inhomogeneous atmospheric duct over the oceans is mainly carried out.The main research contents and results are as follows:1.Aiming at the marine inhomogeneous atmospheric duct environment,the prediction model of horizontal inhomogeneous evaporation duct and the threedimensional parabolic equation model suitable for the inhomogeneous atmospheric environment are established respectively.2.The principal component analysis(PCA)method is used to construct the hybrid horizontal inhomogeneous atmospheric duct model in various scenarios.The propagation characteristics of horizontal inhomogeneous atmospheric duct and horizontal homogeneous atmospheric duct are compared and analyzed.The results show: If the transmitting antenna is located in the duct layer,the horizontal inhomogeneity leads to the increase of propagation loss when the receiving antenna is also located in the duct layer.When the receiving antenna is located outside the duct layer,the influence of horizontal inhomogeneity is small.In the hybrid inhomogeneous duct environment,the distribution of propagation loss is complex.And the propagation loss at long distance may be smaller than that at short distance.3.Based on the sea trials measured data,the three-dimensional parabolic equation(3DPE)and the prediction model of inhomogeneous evaporation duct are preliminarily verified.The results show that the three-dimensional parabolic equation is better than the two-dimensional parabolic equation in the thesis.It also shows that the horizontal inhomogeneous model constructed is more suitable for the study of evaporation duct propagation over the oceans. |
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