VLF/ELF radiation patterns of arbitrarily oriented electric and magnetic dipoles in a cold lossless multicomponent magnetoplasma

Authors

  • T. N. C. Wang,

  • T. F. Bell


Abstract

With the use of a power integral formulation, a study is made of the VLF/ELF radiation patterns of arbitrarily oriented electric and magnetic dipoles in a cold lossless multicomponent magnetoplasma. Expressions for the ray patterns are initially developed that apply for arbitrary values of driving frequency f, static magnetic-field strength equation image, plasma density, and composition. These expressions are subsequently specialized to VLF/ELF radiation in a plasma modeled on the magnetosphere. A series of representative pattern plots are presented for frequencies between the proton (fpH) and electron (feH) gyrofrequencies. These patterns illustrate the fact that focusing effects that arise from the geometrical properties of the refractive index surface tend to dominate the radiation distribution over the entire range feHf ≥ 4.6 fpH. Focusing effects are particularly strong in the range ½feHffLHR, where the major lobe of the pattern lies along equation image and the lobe intensity varies inversely as the first power of the distance between source and observer rather than as the square of this distance. It is concluded that focusing effects should be of significant importance in the design of a VLF/ELF satellite transmitting system in the magnetosphere.

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