Questions tagged [nvis]

Near Vertical Incidence Skywave refers to (normally HF) signals being radiated nearly vertically from the antenna, then reflected in the ionosphere resulting in an almost circular transmission coverage pattern. It is achieved by placing the antenna at low height and is commonly used for near-range communications on the lower HF bands, particularly 3.5 MHz.

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Can a vertical antenna be used for NVIS?

I know that verticals are normally chosen for their low angles of radiation without obscene heights, but I'm not especially interested in DX and am primarily looking for local coverage via NVIS. I've ...
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How to determine antenna height for given HF frequency and coverage radius?

I'm planning on setting up a low-HF antenna for near to mid-range contacts. In my particular case, ideally I would like to be able to cover a radius of approximately 1000-1200 km with good ...