Simulation of Near-distance Propagation of Artificial ULF Source in Anisotropic High Ionosphere

The numerical simulation of the near-distance propagation of the generated ultra-low frequency (ULF) virtual antenna by modulated heating of the high ionosphere is crucial for understanding and interpretating observations from various platforms including ships, aircraft and satellites. In this study, we establish a source that radiating ULF waves from the upper hybrid altitude to the ordinary (O-mode) wave reflection altitude, which can be considered as an antimagnetic circular antenna array. By employing the full-wave method, we obtain the spatial radiation distribution of ULF electromagnetic waves. Analyzing the ground radiation at high latitude EISCAT and low latitude Qingdao, it reveals symmetric concentric circles for horizontal magnetic fields received on the ground at high latitudes and asymmetric concentric circles at middle latitudes around the heater. Additionally, there exists an amplitude minimum around the heater at high latitude, which agrees with experimental results.