{"references": ["Gillies, R. G., G. C. Hussey, G. J. Sofko, and H. G. James (2012), Modeling measurements of ionospheric density structures using the polarization of high-frequency waves detected by the Radio Receiver Instrument on the enhanced Polar Outflow Probe, J. Geophys. Res., 117, A04316, doi:10.1029/2011JA017457", "Pandey, K., Eyiguler, E. C. K., Gillies, R. G., Hussey, G. C., Danskin, D. W., & Yau, A. W. (2022). Polarization characteristics of a single mode radio wave traversing through the ionosphere: A unique observation from the RRI on ePOP/SWARM-E. Journal of Geophysical Research: Space Physics, 127, e2022JA030684. https://doi.org/10.1029/2022JA030684", "Yau, A. W., & James, H. G. (2015). CASSIOPE enhanced polar outflow probe (e-POP) mission overview. Space Science Reviews, 189(1), 3-14.", "Danskin, D. W., Hussey, G. C., Gillies, R. G., James, H. G., Fairbairn, D. T., & Yau, A. W. (2018). Polarization Characteristics Inferred from the Radio Receiver Instrument on the Enhanced Polar Outflow Probe. Journal of Geophysical Research: Space Physics, 123(2), 1648\u20131662. https://doi.org/10.1002/2017JA024731", "Eyiguler, E. C. K., Danskin, D. W., Hussey, G. C., Pandey, K., Gillies, R. G., & Yau, A. W. (2022, May). Satellite attitude effects on the reception of transionospheric HF signals: Examples from the Radio Receiver Instrument onboard e-POP/Swarm-E. In 2022 3rd URSI Atlantic and Asia Pacific Radio Science Meeting (AT-AP-RASC) (pp. 1-4). IEEE.", "Born, M., & Wolf, E. (1980). Principles of optics: Electromagnetic theory of propagation, interference and diffraction of light (6th ed.). Oxford, UK: Pergamon Press."]}

The Radio Receiver Instrument (RRI) on e-POP/Swarm-E has a cross-dipole antenna capable of observing HF radio waves. Slew-to-transmitter passes, in which the antenna boresight direction is aligned with the ray direction are the ideal cases to observe the full polarization ellipse. From the voltages on the dipoles, the polarization characteristics, such as the ellipticity angle and the orientation angle can be determined. However, the RRI may not always be in an optimum position to observe the full signal. In such cases, the polarization characteristics cannot be fully captured. The effects of dipole boresight pointing on the observed orientation angle variations during Faraday rotation periods are presented in detail.