多径衰落的数学模型及分析

多径效应是影响低仰角测控系统正常工作的重要因素。介绍了多径效应产生的机理,建立了多径衰落的数学模型。无线电信号在收发天线间传播时,存在直射路径和多条反射路径,当直射信号和反射信号相互抵消时就会产生多径效应。依据建立的数学模型,分析了多径衰落产生的条件和对系统影响的程度。多径衰落产生的位置由地面站天线高度、飞行器飞行高度和二者之间的距离决定,多径衰落深度主要由地面对电波的反射系数决定。在上述分析的基础上,提出了避免和减小多径衰落对系统影响的几种措施。

Mathematical Model and Analysis of Multipath Fading

Multipath effect is an important factor that affects capability of TTC system at low elevation angles.The principle of multipath effect and the mathematical model of multipath fading are introduced in this paper.While electromagnetic wave travels between transmitting and receiving antennas,it has one direct path and several reflective paths.It will produce multipath fading when reflective signal counterbalances direct signal.Based on the mathematical model,the conditions in which the multipath fading appears and the influences of multipath fading on TTC system are analyzed in this paper.The position where multipath fading appears depends on the altitudes of the both antennas and the distance between them.The intensity of multipath fading depends on the reflectance of surface.Some methods are summarized to avoid and overcome multipath fading.