Here is an interesting White Paper from DX Engineering about building a NVIS type antenna. Thanks Lloyd KC5FM & Ron W5MPY for passing this along.
Near Vertical Incidence Skywave (NVIS) is a propagation mode which uses high angle radiation to send signals almost straight up to be reflected back to Earth for very effective short to medium distance communications. This mode of operation makes it ideal for in-state communications during disasters or other emergency situations. The military has used NVIS techniques for decades to provide short haul communication with other units on the ground.
Oklahoma Section Emergency Coordinator
Amateur Radio Emergency Service
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Are you putting up an NVIS antenna this year?