NVIS Antennas

[clint]

I have been doing some research on NVIS antennas. Lots of set ups designed for EMCOMM out there. Would like to hear from anybody who has actually built or used one.  The military uses these pretty heavily. There are three basic types and I have a new design in mind. If you have experience and comments let me know.



73

KB6CLA

And because I'm sure someone will ask...

NVIS = Near Vertical Incidence Skywave
EMCOMM = Emergency Communications

These are antennas that aim high frequency transmissions
(5 to 30 MHz) almost straight up to bounce back in an inverted cone for close range HF communication. FEMA uses these for short range HF work. They are ideal for using HF over the Mountains from our side to the LA Basin/San Bernardino side.

[CA5th]

Look at this link.  I may try to make one this weekend.

http://www.vcars.org/tech/NVIS.html

[clint]

Yeah, I found all the stuff on the web. There are just so many different designs that I wanted an opinion of people who may have used some of the different ones. We played around with a horizontal dipole and ground reflector type on the AC-100 years ago. I talked to the one guy I trust at HRO today and he actually is already doing what I was planning on trying so I think I'll try a low mounted ham stick dipole with and without the +5% reflector element. I like the one you found too Miles, but it's not very field portable. There is also a design for a single resonant long wire using your car as the ground side. I  may try that using a 50' roll up tape measure as the element. It will be fun to play around with these.

73

KB6CLA

[CA5th]

I also found a portable one.  I am going to try those designs out first.  We will have to compare what we come up with.

[kew]

I just looked up those "portable" antennas. They don't quite fit in my definition of portable.