NVIS

[Jackalope]

 Near Vertical Incidence Skywave (NVIS) is a technique using HF transceivers and properly placed antennas which produces reliable short range communications over varied terrain.  The technique was discovered by the Germans during World War II and improved upon by the U.S. during the Vietnam War.  The technique was later used by allied forces during the Iraq War.

  So why is NVIS useful for preppers?  NVIS is effective for up to 300 miles using low powered radios and relatively simple antennas.  A big plus is that when using this technique it is difficult for other parties to triangulate on your signal, which means your transmitter will be difficult to discover if someone is attempting to locate your radio.  The technique actually works better in valley locations rather than on mountain tops.  The antennas are placed low to the ground, and the antennas can be very discrete.  If you need to keep in contact with local and regional folks, it's a great way to communicate, without having to rely on external equipment, like repeaters.

   Johny suggested this link as an introduction to NVIS: http://kv5r.com/ham-radio/nvis-antennas/  The website provides a more than adequate introduction to NVIS.  If you wish to construct your own NVIS antennas, here are a couple of websites:
 http://arrl-ohio.org/SEC/nvis/Modified%20AS-2259%20NVIS%20Antenna.pdf  and  http://static.dxengineering.com/pdf/WP-NVIS-Rev2.pdf   

    For those that wish to purchase their NVIS antennas, here are a couple of sites: http://www.hamsource.com/nvis.html and for those that want the "best": http://store.armyproperty.com/products/as-2259-gr-antenna-nsn-5985-00-106-6130.html   

     For those preppers looking for a way to communicate locally, this is another tool in your radio tool kit.

[JohnyMac]

After we said our 73's Jackalope I was thinking (Always a scary proposition) I wonder if NVIS would work for other frequency's specifically 2 meter.

With the advent of economically priced BaoFeng's and other Chinese radios 2 meter radios, what a great antenna concept if the grid went down and repeaters were not available. I suspect you could use a simple J pole with ladder line BUT would you get the same characteristics as with a NVIS antenna.

There are plenty of 3 element quad 2 meter antennas out there that would be able to send 20-30 miles BUT it would be easy to DF. A NVIS antenna would make DFing more difficult and reach out to the 20-30 miles.

Interesting subject folks.

[Jackalope]

  Unfortunately NVIS won't work with 2 meters because of the method of propagation and the layers of ionosphere that NVIS uses.  NVIS is used primarily on 80, 60 and 40 meters.

If I was concerned about DFing on VHF, then I'd suggest a yagi antenna, with as many elements as you could realistically use.  A 2 meter antenna with multiple elements would send a relatively tight beam, and if both stations were using yagis, you could reduce power and hopefully also reduce the chance of someone detecting your station.  I would operate outside my AO and use a portable yagi, like this one http://www.arrowantennas.com/arrowii/146-3ii.html   Of course if you went the UHF route, then you would have yagis that have a smaller physical size, but you could have more gain with more elements.  Arrow antenna makes VHF and UHF portable yagis, and I believe they'll also double as hiking sticks.  They also make combination antennas for satellite work, so you could use both VHF and UHF, whichever would work best for your situation.

[JohnyMac]

Great stuff Jackalope 

Here is a link to a backpacking 3 element Quad. Similar to a Yagi antenna. Notice all of the elements are stored in the 32" beam. I am thinking of making one. Deciding to use dowels or fiberglass rods. I really like the arrow nocks for the wire.