[Milsurplus] PRC-74 & NVIS

[Michael Tauson]

On Sat, Jun 14, 2008 at 4:24 AM, Gene Smar <ersmar at verizon.net> wrote:

>     What an NVIS antenna does is put a signal into a zone on the ground that is an annular
> region extending from about 200-500 miles or so from the transmitter.

This is why it's used in Hawaii for HF EARC nets.  Well, that and
geography.  From the Big Island to Kauai is around 250 miles with Oahu
(major population center) closer to the Kauai end.  Being volcanic in
origin, there's a lot of vertical with the old cones and, in the case
of the Big Island, not so old cones getting in the way.  It doesn't
take a whole lot of power but it does require that the atmosphere be
cooperative which, at the moment, isn't happening as much as would be
nice.

One other note is that soil quality also affects transmission.  Oahu
has poor soil (electrically) so reflector wires have to be laid under
the antenna elements to make them work properly.

Okay, that was more than anyone asked about.

Best regards,

Micahel, WH7HG