$GTCH The use of NVIS propagation requires efficient antenna and frequency selection. Particular antenna styles are necessary in order to ensure efficient coverage at all terrain types. This type of antenna and transmission technology is an effective solution in topographical areas where the radio signal is masked or shadowed (for example mountainous or hill areas). NVIS enables having a radio signal with a high angle of elevation that is not shielded by the terrain and therefore can cover HF dead zones as a compliment to the long-range HF communication. This type of antenna and transmission technology can potentially fit to a long-range HF radio communications application; especially, for remote rough geographical regions where essential communication may be needed. GBT will be using advanced antennas to radiate most of the power at a high angle, near to the vertical.

https://www.nasdaq.com/press-release/gbt-near...2021-08-19