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bacpacker
01-27-2012, 01:03 AM
I know we have a few hams on here and would like to pick your brains a little. I need to put up a HF antenna for here at the house. I would also like to build one to take with us when we go camping or to use for a stationary set up, say if we were in a bugout situation.

Here is a couple of designs I ran across yesterday and wanted to see if anyone had expereince with a NVIS antenna.

Quick, Easy, Cheap, NVIS Antenna for Roadside Operating. (http://www.hamuniverse.com/k6sojnvis.html)

DESIGN THE CLOUD WARMER NVIS BEAM ANTENNA (http://www.hamuniverse.com/nvisbeam.html)


I have also looked seriously at these two for use around the house.

MULTI BAND HF FAN DIPOLE ANTENNA DESIGN (http://www.hamuniverse.com/multidipole.html)

New Carolina Windom by K4IWL - Len Carson - Carolina Windom Project - New Version! (http://www.hamuniverse.com/k4iwlnewwindom.html)

The first one is similar to one a friend of mine built with good success. The second one is the same as another friend of mine has up and is making good contacts with it.

Ideas anyone?

austinrob
01-27-2012, 02:35 AM
Look into yo-yo antennas (http://www.hamradiofun.com/yoyodeluxe.html). It's basically 2 spools of really thin wire that you let out to your desired transmitting length. There a bunch, and you can make your own, but the one in the link will do 100W. You can pre-tune them and mark the wire for different bands. That prevents the need for an antenna tuner. I have a friend that uses yoyo's when he goes backpacking. He uses them in an inverted V configuration because it's easier to string up, but given trees in the right place, a plain dipole wouldn't be hard to rig with them either.

For home, I've had really good luck with a windom. I use the design at rogertango (http://rogertango.com/articleread.aspx?idnumber=64229534) at the house here operating 100W. With the antenna laying on my second story roof, it's almost NVIS on 80m, but I can work the continent on 40m, and the world on 20m (when the band cooperates). With a tuner, I have that antenna working everything 80-10m except 12m.

Fan dipoles can be a pain to tune. I tried once and never quite got it right, really had to use a tuner all the time. With my windom, I have usable SWR on 10,20,40,80 without a tuner.

bacpacker
01-27-2012, 12:14 PM
My buddy with the windom has had good luck with his. Ran a contest or 2 with it. The guy with the dipole is retired and will spend days tweaking on it till it perfect. He don't run a tuner on it and gets out great.

I've never looked at the yo-yo before. I'd love to have something small gor backpacking.

austinrob
01-27-2012, 08:32 PM
this place (http://hamwaves.com/cl-ocfd/) explains why/how multi-band antennas work (in particular the off-center fed dipole, aka windom). And it also has a design for a 6-band no-tune windom.

I don't quite get it all, but it provided me with enough insight that I felt more comfortable building the rogertango design.