This concept will work even if you are in a valley and not on the top of a hill! The
radio signal is sent up to be reflected back down by the ionosphere and provide
complete coverage in approximately a 150 mile radius,  with No Skip Zone!

Get the NVIS book Near Vertical Incident Skywave Communications,
by  LTC avid M. Fiedler & MAJ Edward J. Farmer, from Worldradio Products ,
PO Box 189490, Sacramento, CA 95818-9490. It costs  $14.00 plus $2.00
($4.00 non-US ZIP air delivery) CA residents include $1.05 tax.
This book is the current "Bible on NVIS" and is and is well worth it.

FM 24-18 Field Manual  -  Single Channel Communication Techniques 
Read, XXII, Appendix M,  Near-Vertical incidence sky-wave propagation concept

The Dave Fiedler Collection At Army Communicator On - Line
Read his VHF, HF & NVIS Communication articles

Join the listserv at  NVIS-subscribe@yahoogroups.com which discusses using the NVIS technique. or you can go directly to the group's yahoo web pages at http://groups.yahoo.com/group/NVIS .

Be sure to see the fine NVIS information at Tactical Link Systems and also
look at the tactical HF Pack and antenna on the Bonnie Crystal webpage, here
go to HF pack, them about 1/2 way down to MiniBac Antenna, non-commercial
use authorized. San Jose OES / RACES also has a NVIS Section. K5EPH
has a great page on NVIS for emergency groups such as ARES/RACES.

Wellington Mountain Radio Service rents 1W radios for mountainous NVIS

Near Vertical Incidence Scattering Antenna  by Dr. Carl O Jelinek N6VNG
His copy of the AS-2259 which you can build,  and much more inexpensive than the Military Model.

TM 11-666 Antennas and Radio Propagation US Army, February 1953

LDG Electronics  LDG Electronics line of Automatic Antenna Tuners, look at the AT-11MP