Faraday rotation of a polarization plane of over horizon UHF radar signals

 

A. V. Moshkov, V. N. Pozhidayev

Kotelnikov Institute of Radioengineering and Electronics of Russian Academy of Sciences, Mokhovaya str. 11-7, Moscow 125009, Russia

 

The paper is received on March 12, 2018

 

Abstract. Over-horizon ground-based radars in UHF range are widely used for the atmosphere condition and near-earth space monitoring, the moving objects control in the atmosphere, in the meteorology observations and so on. The modern radars, as a rule, are employing widely the polarization descriptions of a signal to get the required information. The range increasing up to several thousand kilometers for such radars leads inevitably to the fact that the part of a signal route will be inside the Earth ionosphere. Even if one can consider that this part of a route is not affected by the sizeable heterogeneity of a media (the ionosphere is practically transparent for the 0.3…2 GHz frequency range) the polarization of a signal is influenced by the Faraday’s effect. For example, the on-board SAR signal processing in L and P wavelength ranges requires to employ the specially designed algorithms. The task of this article is to calculate the possible values of a Faraday’s rotation angle for polarization plane of a signal in case of a long-range over-horizontal radar in UHF. The calculations have been carried out for the different geographic conditions and signal propagation directions. Moreover, the geomagnetic field values during the calculations have been extracted from the generally accepted model IGRF-12 (epoch 2015). This model usage permits to estimate the accuracy of Faraday’s angle calculations as sufficiently high. It is shown that maximum polarization rotation angle value is varied in relatively wide range from ~10º up to nearly 180º over UHF frequency range. The angle value strongly depends on proximity of global geomagnetic field anomalies.

Key words: Earth’s ionosphere, geomagnetic field, Faraday’s effect, radar signals polarization numerical calculation.

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For citation:
A. V. Moshkov, V. N. Pozhidaev. Faraday rotation of a polarization plane of over horizon UHF radar signals. Zhurnal Radioelektroniki - Journal of Radio Electronics. 2018. No. 3. Available at http://jre.cplire.ru/jre/mar18/5/text.pdf
DOI  10.30898/1684-1719.2018.3.4