Effect of the equatorial plasma bubbles on amateur radio communication: Full-wave simulation Study

We present the impact of equatorial plasma bubbles (EPB) on high-frequency (HF) wave propagation, such as amateur (ham) radio communications, in the ionosphere. Ionospheric density irregularities occur over a wide range of latitudes from the equator to the polar region and local times. Many numerical efforts have been made to study wave propagation in the ionosphere; however, several challenges arise in modeling the propagation of HF waves. For example, the wavelength of radio waves in the ionosphere is much shorter than the ray path and the thickness of the ionosphere; thus, simulating these waves requires high-performance computing resources. This challenge is one reason why previous research has predominantly focused on ray tracing and analytical calculations. For such reasons, the properties of HF waves—such as reflection, refraction, scattering, and scintillation—are not fully understood in the context of density irregularities. This presentation introduces the state-of-the-art full-wave simulation code, Petra-M.  We then conduct numerical examinations of how the EPB affects HF wave propagation. We utilize density irregularity structures, such as EPBs, derived from other simulations as background ionospheric density structures. Due to the small-scale density fluctuations in the EPB, HF waves can reach higher altitudes with scattering and trapping in the density structure. Mode conversion from the incoming HF wave to the electrostatic waves, which are localized waves in the ionosphere, also occurs. Such effects can lead to failed wave detection at the receiver since the wave power reaches a broader area near the receiver due to scattering, and wave power can decrease because of the wave mode conversion.