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Dynamics Analysis of a VLF Linear Antenna in an Anisotropic Magnetoplasma

The motion of a very-low-frequency (VLF: 3–30 kHz) orbiting antenna across the Earth’s magnetic field will generate the Lorentz force, which not only compromises the efficiency of the antenna, but also causes it to fall out of orbit over a long time. This article investigates the Lorentz force and dissipated power of a VLF space-borne linear antenna in an anisotropic magnetoplasma as well as the deorbiting time of the system. By considering the inhomogeneity of the current and the effect of ordinary and extraordinary waves, we systematically quantified and analyzed the Lorentz force on the antenna in an anisotropic scenario. The dissipated power and system deorbiting time are then determined by integrating antenna theory and electrodynamics. The results show that the Lorentz force and the power will increase with the antenna length and radius, whereas the deorbiting time will decrease accordingly. It is also found that as the geomagnetic inclination angle increases, the Lorentz force and the power will slightly decrease. The proposed method can estimate the Lorentz force, power, and deorbiting time for arbitrary antennas, low Earth orbital conditions, and VLF ionospheric parameters. This work may also help eliminate the adverse effect and evaluate the deorbiting performance of the VLF space-borne system from an analytical perspective.