Abstract: Polar ionospheric heaters operated by HARRP and EISCAT have generated extremely low frequency waves by modulating the auroral electrojet at D and E region altitudes. However, the auroral electrojet often varies over time and is not always present. Alternatively, modulated F-region HF heating can generate ionospheric diamagnetic current, and the periodic modulation results in a magnetic moment that radiates extremely low frequency waves. Based on a one-dimensional time physical model of polar ionospheric heating and a full-wave model, we analyzed the features of extremely low frequency waves over Tromsø (69.59°N, 19.23°E). The results showed that extremely low frequency waves on the ground are different from lower ionospheric modulation, i.e., radiation of polar electrojet antenna. Furthermore, effective radiated power (ERP), modulated frequency, and ionospheric background, have significant influence on the generated extremely low frequency wave.

Key words: Ionospheric heating, diamagnetic current, extremely low frequency waves, polar electrojet