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首页> 外文期刊>Proceedings of the IEE - Part III: Radio and Communication Engineering >The propagation of metre radio waves beyond the normal horizon. Part 1: Some theoretical considerations, with particular reference to propagation over land
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The propagation of metre radio waves beyond the normal horizon. Part 1: Some theoretical considerations, with particular reference to propagation over land

机译：电表无线电波的传播超出正常水平。第1部分：一些理论上的考虑，特别是在陆地上的传播

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摘要

The effect on radio wave propagation of departures from the normal variation with height of the refractive index of the lower atmosphere is considered with special reference to frequencies of 90 and 45 Mc/s. The relative importance of changes in refraction near the surface of the earth and of reflection from high-level inversion layers is investigated, and some illustrative examples are worked out. The number of parameters concerned in the problem prevents an all-embracing survey of the many possibilities within the scope of the present work, but a few general conclusions are reached. It is unlikely that radio ducts of sufficient magnitude to be greatly significant at the frequencies in question can be maintained over long distances in broken country. Of the two mechanisms????????refraction near the surface of the earth and reflection at an elevated inversion layer????????the latter is the one which is likely more often to give abnormally high field strengths at ranges of a few hundred kilometres, especially for relatively low terminal points. Consideration is also given to the effects of scattering of radio energy by turbulent eddies in the atmosphere, and an approximate calculation is made of the magnitude of this scattering for horizontally polarized waves on a frequency of 90 Mc/s, and at distances up to 500 km. It appears likely that such scattering is of less importance in the creation of unusually high field strengths up to distances of the order of 250 km than the mechanisms of abnormal refraction, including reflection at elevated inversion layers.
机译：特别考虑到90和45 Mc / s的频率，可以认为偏离正常变化的电磁波对下部大气折射率高度的影响。研究了近地表折射变化和高层反演层反射变化的相对重要性，并给出了一些说明性例子。问题中涉及的参数的数量阻止了对本工作范围内许多可能性的全面研究，但得出了一些一般性结论。在破碎的国家中，不可能在远距离上保持足够大的无线电波导管，以在所讨论的频率上具有非常重要的意义。在这两种机制中，靠近地球表面的折射和在升高的反型层上的反射，后者是更可能产生异常高场强的一种。在几百公里的范围内，特别是对于相对较低的终点。还考虑了大气中湍流涡流对无线电能量的散射影响，并对水平极化波在频率为90 Mc / s且距离最大为500时的散射幅度进行了近似计算。公里在产生高达250 km的距离的异常高的场强方面，这种散射似乎比异常折射的机制（包括在反演层高处反射）的重要性低。

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