80 Meter NVIS Antenna – Don’t Get Hung Up on Theory
UPDATE: Since this article was originally published, I went to the pesky South Arm NEFR stage and did an official 80-meter NVIS test with four other seasoned operators. CLICK or TAP HERE to read about the successful test and listen to the actual audio recording of the test.
Watch the following video to see how to build and erect a basic 80-meter NVIS antenna. After watching the video, please read the field test stories below the video as this design flies in the face of a theoretical 80-meter NVIS antenna design.
CLICK or TAP HERE to download a simple plan and material list of this antenna.
CLICK or TAP HERE to purchase the banana post BNC connector to build the NVIS antenna in the video below.
IMPORTANT NOTE: Since the video was created, I’ve switched to wonderful fiberglass electric-fence posts instead of the cumbersome wood stakes you see in the video.
CLICK or TAP HERE to get the affordable fiberglass posts. You’ll need 8 of them. You may be able to get them locally at a Tractor Supply store – and for less money.
Field Testing Tales
I was first introduced to this simplistic antenna in 2014 when I first started to learn CW. My mentor Jim Cluett, W1PID told me about his discovery of this low-to-the-ground antenna because he used it to get onto the NH-VT traffic net each night from his home in Sanbornton, NH.
We have a very difficult communications issue on one of our stages in South Arm, Maine at the rally. CLICK or TAP HERE to read about this tough comms problem. This year, 2019, was my second year in the job and I decided to do an experiment with 80 NVIS with two other operators.
I set up this same antenna as you see in the video above, but it was even more wretched. It averaged just 18 inches above the ground. I was transmitting at 13 watts on my Elecraft KX3 and two other operators heard me crystal clear ten miles away. It’s very likely the success was due to a ground wave.
However, during the same test, my mentor 100 miles away was monitoring the test out of general interest and he heard me just fine. I had a conversation with him while I was waiting for my fellow operators in Maine to set up their 80-meter NVIS antennas just 10 miles away.
We were operating phone (SSB) because that’s how the comms would happen during the race. I’m doubtful my meager 13-watt signal would travel 100+ miles via ground wave over some semi-mountainous terrain, but I could be wrong. It absolutely might be why the other two operators were able to hear me and I hear them just ten miles away.
A week prior to the test at South Arm during July of 2019, I did a similar test with this antenna design in my backyard. That antenna was probably only 30 inches above the ground. I had successful SSB communications with my mentor who was 8 miles away and another old friend, Dave Benson, K1SWL, who was about 40 miles away. Once again, I was fairly low power, 10 watts, and I don’t believe that ground wave would make it 40 miles.
If you’re an antenna expert and can point me to a document that really shows how far an 80-meter ground wave can travel at different power levels, I’d be forever grateful. Please add those links in the comments below. 73 Tim Carter – W3ATB