Effect of Density Irregularities on Radio Frequency Wave Propagation in Ionospheric Plasmas

¹ Princeton Plasma Physics Laboratory, Princeton, New Jersey, USA
² Andrews University, Berrien Springs, Michigan, USA
³ Applied Physics Laboratory, Johnson Hopkins University, Laurel, Maryland, USA

^* Corresponding author: ehkim@pppl.gov

Published online: 7 January 2026

Abstract

Density irregularities play a vital role in determining how radio frequency (RF) waves travel through plasmas. In the Earth’s ionosphere, these density irregularities also impact radio communication. In this study, we conduct a detailed numerical analysis of RF wave propagation in small-scale ionospheric density irregularities using the advanced Petra-M code. We focus specifically on high-frequency (HF) waves, ranging from 3 to 30 MHz, which are essential for military, amateur radio operators, and emergency communications. By introducing density structures, such as equatorial plasma bubbles derived from fluid simulations, we demonstrate that HF waves can scatter in multiple directions when they encounter these irregularities. Additionally, we observe significant mode conversion, where incoming electromagnetic waves transform into electrostatic modes within the density gradient layer. This shows that smaller density irregularities can greatly weaken signals or cause complete signal loss for receivers, emphasizing the need for increased awareness and innovative solutions in radio communication transmission.