This can leave a skip zone of at least 80 to 113 kilometers (50 to 70 mi) where HF communications will not function. Sky waves, generated by standard antennas (for example, doublets) which efficiently launch the sky wave, will not return to earth at a range of less than 161 kilometers (100 mi).

Under actual field conditions, this range can be much less, sometimes as little as 3 kilometers (2 mi). Under ideal conditions, ground wave component of a radio wave becomes unusable at about 80 kilometers (50 mi) (fig 2-12). Problems Encountered in Propagation of Radio Waves With this reliance on HF radio, communications planners, commanders, and operators must be familiar with NVIS techniques and their applications and shortcomings in order to provide more reliable communications. It may also provide the first long-range system to recover from a nuclear attack. It will be the first, and frequently the only, means of communicating with fast-moving or widely separated units. High frequency radio is quickly deployable, securable, and capable of data transmission. Coupling this with the problems that can be expected in deploying multichannel LOS systems with relays to keep up with present and future operation, high frequency (HF) radio and the near-vertical incidence sky-wave (NVIS) mode take on new importance. The standard communications techniques used in the past will not support the widely deployed and the fast-moving formations we intend to use to counter the modern threat. NEAR-VERTICAL INCIDENCE SKY-WAVE (NVIS) PROPAGATION CONCEPT M-1. Home » Ham Radio » NVIS Army FM 24-18Īppendix M with Graphics How to Put MediaInfo in TotalCommander.Dough Types, Procedures, and Properties.How to Become an Amateur Radio Operator.

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