HAM Radio 101

Word of the Day (NVIS): What Does “NVIS” Stand For?

NVIS stands for Near Vertical Incidence Skywave, an ionospheric operating technique that has been used for decades in military and in-state disaster communications. NVIS antennas can be quickly and easily deployed whether camping, on an emergency operation, or for any use where short range HF operation from 80 to 40 meters is preferred.

Here’s how it works: Rather than directing the strongest signals toward the horizon, the NVIS technique calls for directing them straight up, avoiding line-of-sight barriers and providing usable signals anywhere from 30 to 400 miles. Depending on local ionospheric conditions, NVIS antennas work best at frequencies from 2 MHz to 10 MHz. They’re ideal in places where line-of-sight propagation won’t work, such as in mountainous areas.

Here is a video of Tim Duffy, K3LR, DX Engineering’s Chief Operating Officer, discussing the basics of NVIS operation.

DX Engineering carries shortened and full-size 8040 NVIS Antenna Kits, which include a 15 foot portable fiberglass telescopic NVIS antenna mast; 1:1 ratio balun and mounting brackets; low-loss 50-ohm coaxial cable assemblies; premium antenna wire; grounding stakes; glass insulators; antenna support rope; cable strain relief kit; and detailed instruction manual. Kits are also available without antenna masts.

  • The shortened DXE-NVIS-8040S and DXE-NVIS-8040SNM versions feature loading coils to make the 80 meter dipole legs the same length as the 40 meter dipole legs, 34 feet. The antenna fits into a square area about 50 x 50 feet.
  • The full-size DXE-NVIS-8040 and DXE-NVIS-8040NM versions have 67 foot wire dipole antenna legs for 80 meters and 34 foot legs for 40 meters. They fit into a rectangular area approximately 100 x 50 feet. 

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