A Method for O/X Wave Separation in Vertical Incidence Ionograms Based on Polarization Matching Filtering

Ionospheric vertical sounding is a crucial detection technique for both scientific understanding of the ionospheric space environment and engineering applications such as wireless communication and radar. Influenced by the geomagnetic field, the sounding signal splits into ordinary (O) wave and extraordinary (X) wave, which propagate independently in the ionosphere. Correspondingly, both O-wave and X-wave traces appear in vertical incidence ionograms, making precise separation of O/X waves a vital step in enhancing the application value of ionospheric sounding data. However, O/X wave separation is highly challenging due to the complex electromagnetic environment in the high-frequency band, the time-varying, dispersive, and dissipative nature of the ionosphere, as well as technical limitations of the detection equipment itself. This paper proposes an O/X wave separation method based on polarization matched filtering. By fully exploiting the differences in polarization characteristics between O and X waves and constructing matched filters, high-precision separation of the two waves is effectively achieved. Experimental results show that, after polarization matched filtering of the original sounding data, the suppression ratio for orthogonal polarization can reach 80-140 dB. Compared with existing methods, the proposed approach demonstrates significant advantages in separating O/X waves across ionograms of varying morphologies. This method achieves O/X wave separation from the perspective of polarization signal processing, preserves the original polarization characteristics of the detected O/X waves, and carries clear physical significance. It provides a novel approach for modal analytical separation and offers valuable reference for polarization information processing in other applications.