[CALV-AUXCOMM] Calvert AUXCOMM Meeting Thursday March 19 at 7 PM

[Shawn Donley]

All, 
 
Our monthly meeting is this Thursday.  We will be planning for NVIS Day on Saturday, April 25th.
 
NVIS = Near Vertical Incidence Skywave
 
The idea is to launch RF up, not towards the horizon, and use the ionosphere to bounce that signal back to earth over a large radius area, about 300 miles.  Because of the angles involved, only lower frequencies work (i.e. 40M and 80M).  Higher frequencies shoot right through the ionosphere into space.  Look up 
 
More at Near vertical incidence skywave - Wikipedia https://en.wikipedia.org/wiki/Near_vertical_incidence_skywave and elsewhere on the web.
 
April 25th is when Ohio ARES runs its annual NVIS Day but in addition to contacting our Ohio friends, we plan to set up NVIS stations across Calvert as well as outside our EOC and see what coverage we can obtain locally on 80M and 40M (NVIS frequencies).  On Thursday, we'll set up teams and locations.
 
Info about the Ohio ops at https://arrl-ohio.org/nvis/
 
Good NVIS coverage depends upon a suitable antenna.  No vertical antennas unless you bend them to be parallel to the ground.  A low dipole low is a suitable antenna to use, but not too low (see . NVIS N.V.I.S antenna )   https://www.w8ji.com/nvis_n_v_i_s_antenna.htm#:~:text=The%20optimum%20height%20for%20NVIS,%2C%20or%20approximately%2014%2Dfeet.Attached is a 40M/80M cross-dipole design based on the military's AS-2259 antenna.  Optimum height of the center pole is around 35 feet, but 15-20 ft will do with reduced gain towards the zenith. 
 
Some of our older AUXCOMM members built this antenna.  Can you still find it?  Still time to build one too.  If I recall, the number of turns on the loading inductors has been updated.  I'll try to find those changes and pass them on.  You still need an antenna tuner with this antenna.
 
N3AE
Calvert EC