On the assessment of the maximal value the microwave backscattering coefficient amplification within a guiding structure over the sea

Summary form only given. The lower troposphere inhomogeneities, especially ducting, play a dominant role in the design of radar and communication systems working in microwave frequency range over the sea. The available experimental data point to the high probability of temperature inversions and quick humidity decrease for the Black sea region giving rise to over sea duct appearance. It is of great importance to have reliable on-line evaluation of the propagation parameters under local conditions. In this report results are presented from a theoretical investigation of the effect of the microwave backscattering coefficient amplification within an "evaporation" duct. Using seven rays modification of the tree rays propagation model assessment of the maximal possible microwave backscattering coefficient amplification is obtained for both coherent and incoherent components of the scattered electromagnetic field under the idealized assumption of identical upper and lower boundaries. The radiating aerial is supposed submerged within the guiding structure. The computer modeling indicates a more than twenty times amplification factor for the backscattering coefficient for every common target under strong ducting. This very high amplification is due to the interference of the coherent components of the backscattered field and decreases strongly with the increase of the incident angle above the grazing sector. A comparison, with some experimental data is discussed in order to put in practical application the obtained theoretical results