[TMRA] NVIS DAY

[Stephen Bellner]

NVIS Research Paper Available
(from ARRL Bulletin)

A thorough and fully annotated discussion of Near Vertical Incidence
Skywave (NVIS) is available in the research paper, “Radio
Communication via Near Vertical Incidence Skywave Propagation: An
Overview,” by Ben A. Witvliet, PE5B/5R8DS, and Rosa Ma
Alsina-Pagès.

First investigated in the 1920s, NVIS propagation was rediscovered
during World War II as “an essential means to establish
communications in large war zones such as the D-Day invasion in
Normandy,” the paper notes, adding that the US Army subsequently
sponsored a lot of NVIS field research, especially between 1966 and
1973. More recently, NVIS has become a popular means to enable close-in
communication on Amateur Radio HF bands between 3 and 10 MHZ. NVIS can
be used for radio communication in a large area (200-kilometer radius)
without any intermediate manmade infrastructure, and it has been found
to be especially suited for disaster relief communication, among other
applications, according to the paper.
  
“A comprehensive overview of NVIS research is given, covering
propagation, antennas, diversity, modulation, and coding,” the
Abstract explains. “Both the bigger picture and the important details
are given, as well as the relation between them.” As the paper
describes it, in NVIS propagation, electromagnetic waves are sent
nearly vertically toward the ionosphere, and, with appropriate
frequency selection, these waves are reflected back to Earth.
  
In case the link for the research paper gets broken..
https://link.springer.com/article/10.1007/s11235-017-0287-2   

PS..  Ohio’s NVIS antenna day is scheduled for April 22. In addition
to 40 and 80 meters, we want to add 160 and 60 meters (a good 160
antenna should also operate on 60). With the band conditions in the
trash, we need to work up alternative bands and plans to maintain
communications across the state!  These new bands should make for some
interesting antenna construction projects, so get your teams busy!!

Want more information on how to make a NVIS Antenna?  Here’s a link..
http://arrl-ohio.org/SEC/nvis.html