On VLF Radiation Resistance of an Electric Dipole in a Cold Magnetoplasma


  • T. N. C. Wang,

  • T. F. Bell


By using full-wave theory, an analysis is made of the radiation resistance of a short filamentary electric dipole, oriented with an arbitrary angle with respect to the static magnetic field, in a cold, uniform magnetoplasma. The frequency range considered lies below the local lower hybrid resonance frequency and above the proton gyrofrequency, and in this range approximate closed-form expressions for the radiation resistance are obtained by using a plasma model appropriate to the magnetosphere. These closed-form expressions are valid for dipoles of moderately restricted length, and the physical implications of this length restriction are discussed. It is found that the radiation resistance R increases rapidly as ф0, the angle of dipole orientation with respect to the magnetic field, varies from 0° to 30° but only gradually as ф0 varies from 30° up to 90°. The ratio of R0 = 90°)/R0= 0°) is approximately equal to (ƒHe/ƒ)2. Except for the case of parallel orientation and ƒ < 10−2 ƒHe, the radiation resistance of an electric dipole in the magnetoplasma is ∼ 102 to 105 times larger than that in free space. Thus, for the low frequency range considered, an electric dipole in the magnetoplasma is generally much more efficient that it would be in free space.