Escaping the Dead Zone: a Bottleneck in Humanitarian Ionospheric Radio Communications

Abstract

High Frequency (HF) radio communications are used in humanitarian work in areas where local networks are non-existent, or destroyed by natural disaster or human conflict. Direct point-to-point communications are realized over long distances, independent of local networks, using the ionosphere as a natural high-altitude reflector. HF ionospheric radio is essential for humanitarian organizations delivering basic healthcare in poor and remote areas. Normally, with proper frequency planning, ionospheric radio will easily connect all field teams in a contiguous area with a radius of 200-400 km. However, in recent years humanitarian organizations reported a "Dead Zone" that occurs at a short distance from the base, with good reception at larger distances. This local communication blackout causes a security hazard to the field crews. This paper investigates the phenomenon, and makes an inventory of its possible causes and drivers.

Heliophysics and amateur radio: citizen science collaborations for atmospheric, ionospheric, and space physics research and operations

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“…To support work from humanitarian organizations that deliver basic healthcare in low and middle income countries (LMIC), such as Médecins sans Frontières, a group consisting of radio amateurs and scientists established the optimum NVIS antenna height through simulation and measurement (Witvliet and Van Maannen 2005;Witvliet and Van Maannen 2006a;Witvliet and Van Maannen 2006b;Witvliet et al, 2015a). It was shown that the use of mobile whip antennas will result in a Dead Zone between 30 and 60 km of the transmitter due to suppression of high-angle waves (Witvliet, 2021).…”