VHF sporadic E-a significant factor for EMI

Smith, Trevor A.; Igarashi,

doi:10.1109/elmagc.1997.617067

Cited by 6 publications

(5 citation statements)

References 3 publications

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“…Sporadic E can have an important influence on radio communications at HF and above, causing anomalous long-distance ground to ground propagation, at radio frequencies higher than those normally reflected from the ionosphere [17]. This can be problematic for radars operating at UHF and below, as well as for communication systems, particularly those where the angle between the sporadic E layer and the incident radio signal is shallow [18]. Es can also cause radio scintillation at L-band, again for low elevation signals, on both satellite to ground and satellite to satellite paths [19].…”

Section: Introductionmentioning

confidence: 99%

Consolidated Amateur Radio Signal Reports as Indicators of Intense Sporadic E Layers

Deacon¹,

Mitchell²,

Watson³

2022

Preprint

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A case study is presented which demonstrates the value and validity of a novel approach to the use of consolidated amateur (‘ham’) radio reception reports as indicators of the presence of intense ionospheric sporadic E (Es). It is shown that the use of amateur data can provide an important supplement to other techniques, allowing the detection and tracking of Es where no suitable ionosonde or other measurements are available. The effectiveness of the approach is demonstrated by reference to ionosonde data, and the advantages and limitations of the technique are discussed.

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Section: Introductionmentioning

confidence: 99%

Consolidated Amateur Radio Signal Reports as Indicators of Intense Sporadic E Layers

Deacon¹,

Mitchell²,

Watson³

2022

Preprint

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“…Because if its enhanced ionization density, sporadic-E can adversely affect a wide range of radio communications and radar systems, particularly those where the angle between the incident radio signal and the sporadic-E layer is very oblique [1]. Es can also cause scintillation on low-elevation satellite signals, including GNSS [2].…”

Section: Introductionmentioning

confidence: 99%

Evidence for the Magnetoionic Nature of Oblique VHF Reflections from Midlatitude Sporadic-E Layers

Deacon¹,

Mitchell²,

Watson³

et al. 2022

Preprint

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Mid-latitude sporadic-E (Es) is an intermittent phenomenon of the lower E region of the ionosphere. Es clouds are thin, transient, and patchy layers of intense ionization, with ionization densities which can be much higher than in the background ionosphere. Oblique reflection of radio signals in the very high frequency (VHF) range is regularly supported, but the mechanism for it has never been clearly established - specular reflection, scattering, and magnetoionic double refraction have all been suggested. This article proposes using the polarization behaviour of signals reflected from intense midlatitude sporadic-E clouds as an indicator of the true reflection mechanism. Results are presented from a measurement campaign in the summer of 2018, which gathered a large amount of data at a receiving station in the UK using 50 MHz amateur radio beacons as signal sources. In all cases the signals received were elliptically polarized, despite being transmitted with linear polarization; there were also indications that polarization behaviour varied systematically with the orientation of the path to the geomagnetic field. This represents, for all the examples recorded, clear evidence that signals were reflected from midlatitude Es by magnetoionic double refraction.

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“…Because of its enhanced ionization density, sporadic-E can adversely affect a wide range of radio communications and radar systems, particularly those where the angle between the incident radio signal and the sporadic-E layer is very oblique [1]. Es can also cause scintillation on low-elevation satellite signals, including GNSS [2].…”

Section: Introductionmentioning

confidence: 99%

“…In (1), ωN is the plasma frequency (the natural frequency of charge displacement), ωB is the electron gyro frequency (the natural frequency at which electrons rotate around the magnetic lines of force), ωL and ωT are the longitudinal and transverse components of ωB relative to the direction of propagation, and ν is the electron collision frequency. YL and YT are the magnetic terms and Z is the absorption term.…”

Section: Introductionmentioning

confidence: 99%

Evidence for the Magnetoionic Nature of Oblique VHF Reflections from Midlatitude Sporadic-E Layers

et al. 2022

View full text Add to dashboard Cite

Mid-latitude sporadic-E (Es) is an intermittent phenomenon of the lower E region of the ionosphere. Es clouds are thin, transient, and patchy layers of intense ionization, with ionization densities which can be much higher than in the background ionosphere. Oblique reflection of radio signals in the very high frequency (VHF) range is regularly supported, but the mechanism for it has never been clearly established—specular reflection, scattering, and magnetoionic double refraction have all been suggested. This article proposes using the polarization behaviour of signals reflected from intense midlatitude sporadic-E clouds as an indicator of the true reflection mechanism. Results are presented from a measurement campaign in the summer of 2018, which gathered a large amount of data at a receiving station in the UK using 50 MHz amateur radio beacons as signal sources. In all cases the signals received were elliptically polarized, despite being transmitted with linear polarization; there were also indications that polarization behaviour varied systematically with the orientation of the path to the geomagnetic field. This represents, for all the examples recorded, clear evidence that signals were reflected from midlatitude Es by magnetoionic double refraction.

show abstract

VHF sporadic E-a significant factor for EMI

Cited by 6 publications

References 3 publications

Consolidated Amateur Radio Signal Reports as Indicators of Intense Sporadic E Layers

Consolidated Amateur Radio Signal Reports as Indicators of Intense Sporadic E Layers

Evidence for the Magnetoionic Nature of Oblique VHF Reflections from Midlatitude Sporadic-E Layers

Evidence for the Magnetoionic Nature of Oblique VHF Reflections from Midlatitude Sporadic-E Layers

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