Abstract
Near Vertical Incidence Skywave (NVIS) propagation can be used for radio communication in a large area (200 km radius) without any intermediate man-made infrastructure. It is therefore especially suited for disaster relief communication, communication in developing regions and applications where independence of local infrastructure is desired, such as military applications. NVIS communication uses frequencies between approximately 3 and 10 MHz. A comprehensive overview of NVIS research is given, covering propagation, antennas, diversity, modulation and coding. Both the bigger picture and the important details are given, as well as the relation between them.
Highlights
Interest in radio communication via Near Vertical Incidence Skywave (NVIS) propagation has revived, not in the least because of its role in emergency communications in large natural disasters that took place in the last decade [1,2,3]
The block diagram of a Multiple Input Multiple Output (MIMO) NVIS communication system is given in Fig. 2. t can be reduced to a diversity system by omitting the second modulator, transmitter and transmit antenna, or to a Single Input Single Output (SISO)
A large amount of research has already been done on individual components of the NVIS radio communication system, but several subjects remain that merit investigation, to augment or interconnect the existing research
Summary
Interest in radio communication via Near Vertical Incidence Skywave (NVIS) propagation has revived, not in the least because of its role in emergency communications in large natural disasters that took place in the last decade [1,2,3]. The NVIS propagation mechanism enables communication in a large area without the need of a network infrastructure, satellites or repeaters. This independence of local infrastructure is essential for disaster relief communications, when the infrastructure is destroyed by a large scale natural disaster, or in remote regions where this infrastructure is lacking. Typical frequencies are between 3 and 10 MHz. The term ’Near Vertical Incidence Skywave’ was first mentioned by Rufenach et al [6], others claim that Perlman [7] named the propagation mechanism. Research into the improvement of landmobile and airmobile NVIS antennas is from the last two decades [19,20]
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