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对于今后的海洋卫星通信系统中的低G/T(增益/噪声温度比值)舰载地面站来说,在低仰角时由海面反射造成的多路径衰减的效应将是非常重要的。然而,到目前为止,还未建立起供衰减预测用的L波段多路径衰减的切实可行的模型。本文根据有关散射功率的相关和非相关分量作为海面状况函数的遮蔽的克希霍夫近似理论,提出一种实用的衰减模型。在应用这一模型时,理论上的衰减深度是作为仰角、波高和天线增益的函数而介绍的。结果表明,在波高大于50厘米时才会产生强烈的衰减,并且,在这些条件下在L波段频率上波高对衰减的影响很小。理论上的结果和从现场实验得到的结果相当一致。
The effect of multipath fading caused by sea surface reflections at low elevation angles will be important for low G / T (Gain / Noise Temperature Ratio) shipborne ground stations in future marine satellite communications systems. However, so far, no practical model has been established for attenuation of L-band multipath for attenuation prediction. In this paper, we propose a practical attenuation model based on the sheltered Kirchhoff approximation about the correlation of the scattered power and the non-correlated component as a function of the sea surface condition. In applying this model, the theoretical attenuation depth is introduced as a function of elevation angle, wave height and antenna gain. The results show that strong decay occurs at wave heights greater than 50 cm and that the wave height at L band frequency has little effect on attenuation under these conditions. The theoretical results are quite consistent with those obtained from field experiments.