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首页> 外文期刊>Electrical Engineers - Part IIIA: Radiocommunication, Journal of the Institution of >The investigation and forecasting of ionospheric conditions
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The investigation and forecasting of ionospheric conditions

机译：电离层状况的调查和预报

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摘要

A general account is given of British work on ionospheric exploration, conducted by vertical-incidence radio sounding, during the period from 1924 to date. The essential feature of such exploration is the determination of the equivalent height of reflection as a function of radiowave frequency, from which relation the electronic structure of the ionosphere may be approximately deduced. From such verticalincidence measurements it is possible to predict the refractive influence of the ionosphere on waves obliquely incident on it, and thus to estimate, for given ionospheric conditions, the maximum radio frequency which is returned to the ground at any given range from a sending station. Moreover, such estimated maximum usable frequencies for oblique-incident transmissions may themselves be based on a prediction of ionospheric structure made some months in advance. Such advance forecasts of ionospheric-layer electron densities and heights must be based on past experience of diurnal and seasonal behaviour and of the general waxing and waning of ionization densities during the sunspot cycle. Since 1935, measurements of ionospheric layer heights and ionization densities have been supplemented by regular determinations of overall ionospheric reflection coefficients at vertical incidence. In this way some progress has been made in estimating the attenuation of radio waves in practical cases of oblique-incidence reflection. It cannot, however, be claimed that the predictions of ionospheric absorption are yet as reliable as the predictions of ionospheric refraction.
机译：概述了从1924年至今的英国通过垂直入射无线电测深进行的电离层探测工作。这种探索的基本特征是确定等效反射高度作为无线电频率的函数，由此可以近似推导电离层的电子结构。从这样的垂直入射测量中，可以预测电离层对斜入射的电波的折射影响，从而可以在给定的电离层条件下估算从发送站返回到任意给定范围的地面的最大射频。此外，这种估计的斜入射传输的最大可用频率本身可以基于几个月前作出的电离层结构预测。对电离层电子密度和高度的这种提前预测必须基于过去的昼夜和季节行为以及太阳黑子周期中电离密度的一般起伏和减弱的经验。自1935年以来，通过定期确定垂直入射时的总电离层反射系数，对电离层高度和电离密度的测量进行了补充。以此方式，在倾斜入射反射的实际情况下，在估计无线电波的衰减方面取得了一些进展。但是，不能说电离层吸收的预测与电离层折射的预测一样可靠。

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