Isotropic Irradiation Model from Atmospheric Discharges Using Local Atmospheric Electric Field Data

Abstract

Using a local atmospheric electric field sensor network (Field Mill), an electromagnetic link model was proposed considering a free space electric field and a theoretical electric field calculated from an atmospheric discharge. With this, it was possible to compare the theoretical value of this electric field with the experimental value of the local atmospheric electric field (estimated by the Field Mill sensor network). The results are initially analyzed considering wavelengths in the EHF spectrum (λ ~ 10^-5m) and the VLF spectrum (λ ~ 10⁴m). As assumed before, admitting that the lightning channel acts as an isotropic irradiator and a Field Mill sensor acts as a receiving antenna for the spectrum emitted by the lightning, a irradiated power model of the electromagnetic waves reaching the Field Mill sensor, according to the ITU-R P.873.4 standard, was calculated, thus allowing a correlation with a satellite radio link, in which the Field Mill sensor acts as a ground receiving antenna and the main channel of the lightning strikes acts as a transmitting antenna. Also, a model of the power irradiated by each lightning discharge, recorded by the Field Mill sensor network, was proposed, and the Equivalent Isotropically Radiated Power - EIRP was calculated for different values of effective electric field (Eef) and then compared with the model of the power irradiated by the antenna (lightning). This makes it possible to do an analysis and determine if the lightning discharge can be approximated to an isotropically irradiated antenna model.

Keywords:
satellital link; atmospheric electric field; field mil; lightning.

HIGHLIGHTS

• Free-space communication theory using an antenna located on the Earth's surface.

• VLF spectrum represents about 59% of correlation with the free space electric field.

• The EIRP has a result of ~26% for the value between 1000-2000 W.