On 12/31/2010 2:28 PM, Bwana Bob wrote:
> We called it "short skip", during my misspent youth. From my Novice
> days in 1966 to the present, I don't think I've ever had an antenna
> higher than about 25 feet anyway. I work mostly 80 m traffic nets,
> where we're more interested in covering the state than in DX. Years
> ago, I put up a ground mounted trap vertical because there were no big
> trees at the QTH. On 75m I couldn't be heard 5 miles away. I then
> rigged a low 1/4 wave inverted "L" fed at the base of the vertical and
> got instant statewide coverage.
> Today, when I go on vacation with my Ten-Tec Scout, I rig a low 80 meter
> dipole. Operating from a wooded lake valley, I get great signal reports
> on 80, with signal strength at a range of 50 miles as good a my signal
> at 5 miles.
>
> I first heard the term NVIS (Near Vertical Incident Skywave) back in
> 1981. I was doing flight testing some navigation equipment at Lakehurst
> Naval Air Station on NJ and I came a cross a couple of guys with a Huey
> helicopter and an old Dodge M37 truck with some funny antennas on them.
> They called the antennas shorted loops. They were sort of half loops
> with the far end grounded to the helicopter tail boom or to the truck's
> front brush guard. They were simultaneously developing these low-profile
> antennas and experimenting with HF NVIS. The need for this in a
> helicopter came out of the Viet Nam experience where it was proven that
> a high flying helicopter is pretty vulnerable to ground fire. The new
> aviation doctrine that evolved from that is "nap of the earth" (NOE)
> flying where the helo flies low and scoots through valleys and ducks
> behind hills. This kind of flying is not conducive to VHF line of sight
> communication, hence the need for HF NVIS operation. HF NVIS was also
> used during Operation Desert Storm, particularly since there were not
> enough SATCOM channels to go around.
But did they call it NVIS or just short range skip? The concept has been
known and used for most all of radio history, not always planned that
way but used often when hams didn't know better and used the handy phone
wire or fence wire. What we are search for is who thought up the
moniker, not who figured out a need for planning to use the concept.
All the FM24-18 I could find that admitted a date were Sept 30, 1987
which replaced an edition of 1984. The only place I found the 1984 was
willing to sell it, apparently that edition hasn't been scanned. The
alternative question might be when was appendix M added.
>
> Anyway, it works for me and my operating style. I use a low 80 meter
> dipole plus a low 65 foot inverted L as a backup. The big rigs (Paragon
> and Corsair) do fine, but the system works well for the little rigs
> (Scout and Century 22) which only run 20 or 30 watts.
>
>
>
> 73,
>
> Bob WB2VUF
>
It has worked for many for a long long time with being called NVIS.
73, Jerry, K0CQ
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