Near Vertical Incidence Skywave (NVIS) Antennas - AS-2259/GR (Part 1)

Nice presentation. Simple and to the point. As a former Signal Officer in Special Operations I developed my own version of the NVIS antenna for about $70.00 and a couple of days worth of work. The antenna is presently mounted on my roof and works well. Have made contacts over 3200 miles away and as close as the other side of the mountain. Actually made a digital contact in Japan. It works as designed and I would encourage all to have one in their Jump Kit. 73...Matt ~ WD7N

Excellent video! Prices for surplus military is outrageous but seems to be so simple to make.

Thank you for this video. I just passed my general exam and you are answering questions very plainly for a novice like me

Great video. This antenna was used with the PRC-74 and I've also used it with the PRC-104 in 10th and 20th Group. (Back in the day).  There are also DYI designs for a NVIS antenna on-line. (As WD7N mentioned).   73, Tim KB2RLB (currently T6TM)

The 2259/GR is basically 2 inverted-V dipoles crossed 90 degrees at the feedpoint to maximize separation between the dipole elements to keep the horizontal radiation pattern omnidirectional, while maintaining the vertical gain. This is definitely a "compromise" antenna: it's designed for portability and quick/easy to set-up rather than for maximum performance and efficiency. It was designed to be used mainly from 5MHz to 8MHz, so as -is, the dipoles aren't resonant on the amateur bands (with the possible exception of some 60m frequencies), so you will need a tuner. There are several designs available for modifying the element lengths of an existing 2259 for the 'ham' bands as well as lots of How-to's on DIY versions. I built mine for the 40m & 80m bands. The feedpoint and element ends of this type of antenna are so close to the ground that the element lengths are shortened due to "end effects" and other factors. Usng the traditional 1/2 wave dipole formula of "492/f" for the element lengths gave me 40m elements about 3.7ft too long, and the 80m elements were almost 8ft long. So for NVIS dipoles, "440(ft)/freq(Mhz)is a better formula for the 1/2 wave length. If you plan to tune the antenna on-site for the lowest SWR, the feedpoint HEIGHT, the ground quality under the antenna, and the angle formed by the dipole elements will all affect the feedpoint impedance, and therefore the SWR. And for 40m/80m use, a feedpoint height of 35 - 50 ft should be much more efficient, but taller masts mean more poles and extra guying gear.

Thank you for this informative video. I will be referencing this when explaining NVIS to our disaster preparedness committee. We are working on comm plans on our island which has multiple volcanoes that obscure line of sight transmissions between dialysis facilities. regards, Jim WH6FQI

I tried to make part II last week but people kept walking into frame. I need to find a place with some space to setup. Unfortunately, the video will only cover setting up the antenna. I don't have anyone to play the role of the other station to show the antennas actually work (it takes two stations with NVIS antennas).

Thanks - HF is my favorite type of comms.

I used one in Panama in the late 90's with a PRC-104...

It's called EN-VIS and stands for NEAR VERTICAL INCIDENT SKYWAVE. It comes about because of the high takeoff angle of the antenna. You do not need the special antenna to do this. In WW II (when it was "discovered") the GIs merely bent their vehicles' antennas over parallel to the ground.

I remember those...great info.

If your hospitals have the roof space - NVIS antennas are a great option. No I just need to find a place with enough space to setup for the part 2 video.

Radio you're thinking of is the PRC-74.

We will set this NVIS up at camp. Does not look to be a problem at all CP. How will it perform under the cover of trees. Regards, Lars

'65 - '66 we had AN/PRC-25s on either side of the bridge of our destroyer, so that ground troops could request NGFS.

Excellent! Detailed presentation of NVIS. Great Job - Thanks for sharing. Ron KK6URQ

Radio the adapter fits??? Maybe PRC-77. I carryied on on my back sometimes in the Army as late as the beginning of Desert Storm in 1990.

Very well explained. Thanks!

Just make your own. Very easy, very cheap, doesn't requite a lot of work.

thank you for the information !