A circularly polarized, electrically scanned slotted waveguide array suitable for high temperature environments

Stilwell, R.K.; Wallis, R.E.; Edwards, M.L.

doi:10.1109/aps.2003.1220087

Cited by 6 publications

(2 citation statements)

References 3 publications

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“…Pure circular polarization corresponds to an axial ratio of unity for the orthogonal linear electric vectors, meaning no intrinsic linear polarization and therefore no capability to detect FR. However, the MESSENGER transmitter system exhibited a small departure from this ideal state at the nominal operating frequency [ Stilwell et al ., ] corresponding to linear polarization of about 11%, or sometimes more depending on propagation effects. This value is comparable to percentage linear polarization established for extragalactic sources used in prior FR studies [e.g., Ingleby et al ., ] and enabled us to measure FR.…”

Section: Observations and Data Processingmentioning

confidence: 99%

Faraday rotation fluctuations of MESSENGER radio signals through the equatorial lower corona near solar minimum

et al. 2017

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Faraday rotation (FR) of transcoronal radio transmissions from spacecraft near superior conjunction enables study of the temporal variations in coronal plasma density, velocity, and magnetic field. The MESSENGER spacecraft 8.4 GHz radio, transmitting through the corona with closest line‐of‐sight approach 1.63–1.89 solar radii and near‐equatorial heliolatitudes, was recorded soon after the deep solar minimum of solar cycle 23. During egress from superior conjunction, FR gradually decreased, and an overlay of wave‐like FR fluctuations (FRFs) with periods of hundreds to thousands of seconds was found. The FRF power spectrum was characterized by a power law relation, with the baseline spectral index being −2.64. A transient power increase showed relative flattening of the spectrum and bands of enhanced spectral power at 3.3 mHz and 6.1 mHz. Our results confirm the presence of coronal FRF similar to those described previously at greater solar offset. Interpreted as Alfvén waves crossing the line of sight radially near the proximate point, low‐frequency FRF convey an energy flux density higher than that of the background solar wind kinetic energy, but only a fraction of that required to accelerate the solar wind. Even so, this fraction is quite variable and potentially escalates to energetically significant values with relatively modest changes in estimated magnetic field strength and electron concentration. Given the uncertainties in these key parameters, as well as in solar wind properties close to the Sun at low heliolatitudes, we cannot yet confidently assign the quantitative role for Alfvén wave energy from this region in driving the slow solar wind.

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Section: Observations and Data Processingmentioning

confidence: 99%

Faraday rotation fluctuations of MESSENGER radio signals through the equatorial lower corona near solar minimum

et al. 2017

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“…At that point the approach for both the spacecraft and instruments was firm, the planned launch targeted an optimized March 2004 window (Yen, 2001;McAdams et al, 2002), and backup launches in May 2004 and July to August 2004 were identified. The overall spacecraft concept and all subsystems were designed (e.g., Ercol and Santo, 1999;Ercol et al, 2000;Persons et al, 2000;Wallis and Cheng, 2001;Vaughan et al, 2001;Dakermanji et al, 2002;Krupiarz et al, 2002;Nhan et al, 2002;Conde et al, 2002;Ling et al, 2002;Moore, 2002;OÕShaughnessy and Vaughan, 2003;Krupiarz, 2003; Stilwell et al, 2003;Stratton et al, 2003;Hauck and Finnigan, 2003;Heiligman et al, 2003).…”

Section: Design and Developmentmentioning

confidence: 99%