Radiation Resistance of a Short Dipole Immersed in a Cold Magnetoionic Medium

Wang, T. N. C.; Bell, T. F.

doi:10.1029/rs004i002p00167

Cited by 53 publications

(58 citation statements)

References 8 publications

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“…To test this relationship, we can compare the predictions of (28) with the results of Balmain [1964], Wang and Bell [1969], and Wang [1970]. In these studies a triangular current distribution was assumed, implying (b s h) 2 ( 1, and we have seen above that (b c R a ) 2 ( 1 for typical antenna lengths.…”

Section: Antenna Input Impedancementioning

confidence: 99%

“…However, the accuracy of the triangular current assumption has never been established. Numerous references concerning early work on this topic can be found in work by Balmain [1972Balmain [ , 1979, Wang and Bell [1969], and Wang [1970].…”

Section: Introductionmentioning

confidence: 99%

“…These equations are developed in the limit of short wavelengths, ie, for l 2 ( l o 2 , where l o is the wavelength of whistler mode waves propagating parallel to B o . This approach is suggested by the results of Wang and Bell [1969], who assumed a current distribution similar to (1b) and found that the major portion of the radiated power was carried by quasielectrostatic whistler mode waves for which l ' h. This result suggests that if the antenna length is restricted to 100 m or less, one can reasonably neglect the effects of the waves with l ! 1 km and consider only the shorter wavelength quasi-electrostatic waves.…”

Section: Introductionmentioning

confidence: 99%

“…1 km and consider only the shorter wavelength quasi-electrostatic waves. Our second goal is to determine the conditions under which I(s) is approximately triangular in order to judge the applicability of past work [e.g., Balmain, 1964;Wang and Bell, 1969;Wang, 1970] in which such distributions were assumed to apply.…”

Section: Introductionmentioning

confidence: 99%

“…[11] Subsequently, Wang and Bell [1969] and Wang [1970] studied the same problem with the aim of establishing the general characteristics of dipole antennas in the plasmasphere. In contrast to the approximate quasi-static model of Balmain [1964], Wang's model relied on a numerical solution of the full set of Maxwell's equations to find the antenna input impedance, assuming a triangular current distribution.…”

Section: Introductionmentioning

confidence: 99%

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Current distribution of a VLF electric dipole antenna in the plasmasphere

2006

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[1] In a recent paper (Inan et al., 2003) a method of remediating enhanced energetic electron fluxes in the radiation belt was proposed in which injection of VLF whistler mode waves from spacecraft within the radiation belts would dramatically increase the pitch angle scattering of the relativistic electrons and cause these particles to be rapidly lost from the belts, thereby mitigating the flux enhancement. The VLF wave transmitting system discussed by Inan et al. (2003) involves electric dipole antennas. One of the most important characteristics of such an antenna is the current distribution along the length of the dipole, since it is this current which ultimately determines the amount of VLF power which can be radiated from the antenna into the plasma. In past work it has been assumed without proof that the dipole current has a triangular distribution. In the present work we determine the dipole antenna current distribution from first principles, constructing an integral equation of the Hallén type relating the current distribution to the wave vector potential. In this development it is assumed that the length of the thin cylindrical dipole antenna is small compared to the wavelength of whistler mode waves which propagate parallel to the Earth's magnetic field B o . In the case of the dipole antenna oriented parallel to B o , it is found that the assumption of a triangular current distribution is reasonable for antenna lengths up to hundreds of meters. For the case of the antenna perpendicular to B o , it is found that the current decays exponentially along the antenna from the feed points to the antenna ends. In this case we find the conditions under which a triangular current distribution is still a reasonable approximation. We also give the conditions under which the quasi-static model of Balmain (1964) reasonably describes the electric fields associated with the dipole antenna.

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Section: Antenna Input Impedancementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Current distribution of a VLF electric dipole antenna in the plasmasphere

2006

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The effect of electron and ion temperature on the refractive index surface of 1–10 kHz whistler mode waves in the inner magnetosphere

et al. 2015

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Whistler mode waves in the magnetosphere play an important role in the energy dynamics of the Earth's radiation belts. Previous theoretical work has been extended to include ions in the fully adiabatic warm plasma theory. Using a finite electron and ion temperature of 1 eV, refractive index surfaces are calculated for 1–10 kHz whistler mode waves in the inner magnetosphere (L ≲ 2.5). For the frequencies of interest, a finite ion temperature is found to have a greater effect on the refractive index surface than the electron temperature and the primary effect is to close an otherwise open refractive index surface. Including a finite ion temperature is especially important when the wave frequency is just above the local lower hybrid resonance frequency. For wave frequencies more than ∼1 kHz above the local lower hybrid resonance frequency, including the ion temperature has a negligible effect on the refractive index surface calculation. The results are used to assess previous conclusions on whether in situ whistler mode sources can be realistically used to precipitate energetic electrons. It is found that the number of in situ sources needed to illuminate the inner plasmasphere (L≲2.5) with whistler mode energy may be greater than previously predicted.

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