VLF Far-Field Radiation from a Linear Dipole Antenna Immersed in a Plasma: Baseline Model for DSX
Lincoln Laboratory, MIT LEXINGTON United States
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One of the prime objectives of the Demonstrations and Science Experiment DSX satellite mission is to determine the efficiency of injecting power into the magnetosphere at Very Low Frequencies VLF from an in-situ dipole antenna. A baseline VLF antenna radiation model for DSX has been developed using the stationary phase, far-field approximation to obtain a solution to the Greens function for the electric and magnetic fields driven by the antenna current in the limit of cold plasma linear response theory. Estimates of the wave vectors and Poynting flux are output on the surface of a sphere of constant radius assuming a homogeneous plasma. The input antenna currents can either be specified from the data or derived from an impedance relation with the antenna voltages. An example impedance function, that of Balmain, is given and results generated for parameters typical of the DSX plasma environment. The intent of the model is to serve as a baseline linear model to which DSX data can be compared, and the differences used to guide model improvement.
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