Radio Observations of the Ionosphere at Oblique Incidence

Chapman, John H.; Davies, K.; Littlewood, C. A.

doi:10.1139/p55-088

Cited by 10 publications

(5 citation statements)

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“…Faraday rotation due to the geomagnetic field is non-reciprocal in this sense. The failure of the recriprocity for HF ionospheric paths has been reported in previous reports [13][14][15][16].…”

Section: Reciprocitysupporting

confidence: 66%

High-resolution over-the-horizon radars using time reversal

Paek¹,

Choe²,

Bernhardt³

2009

SPIE Proceedings

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A method of high resolution over-the-horizon radars (OTHRs) using time-reversal is described. The method uses timereversal in the multipath-enriched ionospheric environment in order to achieve the extended virtual aperture. Also, the double-pass conjugate image scanning scheme allows imaging of non-cooperative targets without requiring apriori knowledge of environmental conditions. Initial theoretical and experimental results are provided.

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Section: Reciprocitysupporting

confidence: 66%

High-resolution over-the-horizon radars using time reversal

Paek¹,

Choe²,

Bernhardt³

2009

SPIE Proceedings

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“…Note that the current goes to zero at the ends of the antennas. The radiation fields generated by an antenna excited by the current described in Equations (1) and (2) are given by [5,6,13,14]:…”

Section: Expressions For the Current Distribution And The Electromagnmentioning

confidence: 99%

“…The radiation from short dipoles is generally studied to obtain information concerning the electromagnetic radiation generated by oscillating currents; the radiation from quarter-wave and half-wave dipoles tends to be studied for practical applications. Moreover, antennas of varying lengths with oscillating currents are used as receiving or transmitting antennas in many applications in atmospheric research, for example, in the study of electromagnetic wave transmission and reflection across the ionosphere [2]. They are also the receiving antennas of choice in VHF interferometric applications pertinent to the location of discharge activity inside thunderclouds [3].…”

Section: Introductionmentioning

confidence: 99%

On the Remarkable Features of the Lower Limits of Charge and the Radiated Energy of Antennas as Predicted by Classical Electrodynamics

Cooray

2016

Atmosphere

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Electromagnetic energy radiated by antennas working in both the frequency domain and time domain is studied as a function of the charge associated with the current in the antenna. The frequency domain results, obtained under the assumption of sinusoidal current distribution, show that, for a given charge, the energy radiated within a period of oscillation increases initially with L/λ and then starts to oscillate around a steady value when L/λ > 1. The results show that for the energy radiated by the antenna to be equal to or larger than the energy of one photon, the oscillating charge in the antenna has to be equal to or larger than the electronic charge. That is, U ě hν or UT ě h ñ q ě e , where U is the energy dissipated over a period, ν is the frequency of oscillation, T is the period, h is Planck's constant, q is the rms value of the oscillating charge, and e is the electronic charge. In the case of antennas working in the time domain, it is observed that U∆t ě h{4π ñ q ě e , where U is the total energy radiated, ∆t is the time over which the energy is radiated, and q is the charge transported by the current. It is shown that one can recover the time-energy uncertainty principle of quantum mechanics from this time domain result. The results presented in this paper show that when quantum mechanical constraints are applied to the electromagnetic energy radiated by a finite antenna as estimated using the equations of classical electrodynamics, the electronic charge emerges as the smallest unit of free charge in nature.

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“…The Canadian experiments [10,11] made over an east-west path of 2,350 km showed that under certain conditions the Pedersen ray was relatively important and that signals were sometimes received at frequencies up to 10 percent higher than the so-called "classical MUF". In these experiments, good agreement was found between the observed classical MUF's and the MUF's calculated on the basis of Sellmeyer theory.…”

Section: Survey Of Previous Workmentioning

confidence: 99%

“…During the war B eynon (4] extended these experiments to longer path lengths with improvemen ts in the recording technique. After World War II oblique-incidence work was extended to still greater distances in Germany (5 , 6, 7, 8, 9], Canada (10,11,12], the United States (13,14,15], and Japan (16]. I The results of these investigations will be considered in th e following section.…”

Section: Introductionmentioning

confidence: 99%

Ionospheric investigations using the sweep-frequency pulse technique at oblique incidence

Agy¹,

Davies²

1959

J. RES. NATL. BUR. STAN. SECT. D. RAD. PROP.

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This paper describes the prese nt state of obliqu e-in cidencc in vestigaLion s of Lhc ionosphere, using the sweep-frequency pulse technique, with sp ecial reference to the work canied out. at tl?e ~ ational Bureau of Standards. After a short r eview of the publi hed li terature, obhque-lllCldence sweeps are presented showing the diurnal a nd seasonal variations Oll two east-west paths of lengths 1,150 kilometers and 2,370 kilom eters. The discrep ancies between observed and calculated maximum usable frequencies are presented for both p ath s and then various phenomena of interest are shown. Finally, the a bove phenome na are disc ussed in the light of existing knowledge and theory and, in particula r, it i shown that the di screpa ncies between observed and calculated maximum usable fr equ e nci es are unlikely to be caused by magn etoionic d eviation of the ray.

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Radio Observations of the Ionosphere at Oblique Incidence

Cited by 10 publications

References 0 publications

High-resolution over-the-horizon radars using time reversal

High-resolution over-the-horizon radars using time reversal

On the Remarkable Features of the Lower Limits of Charge and the Radiated Energy of Antennas as Predicted by Classical Electrodynamics

Ionospheric investigations using the sweep-frequency pulse technique at oblique incidence

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