NVIS Overview (
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- Опубликовано: 19 сен 2024
- NVIS is Near-Vertical Incidence Skywave propagation. I came across this from an old General training video of mine. It's not in the new (2019) syllabus, so I had to chop it. It seems too good to throw away, though, so here it is--a quick and dirty look at NVIS.
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Thank you for this explanation, Dave. I was on a summits on the air (SOTA) activation over the weekend on 20m and incorrectly stated on my RUclips video that the reason I was making local contacts was due to my antenna being in an NVIS configuration. According to another RUclipsr, he mentioned that based on the frequency I was on, that I was making contacts via ground wave propagation. Your simple, straight forward explanation cleared things up. Keep up the great work. 73, KT1RUN
Utahn here, just found your channel. Glad to know theres a channel that will explain literally anything I have a question about when it comes to RF Theory!
I've setup a few NVIS antennas. Never on purpose though.
I have always struggled to explain NVIS and the term MUF as I would teach license exam material in my past life. Think I got it done, however the way you explain it is much more understandable. Now nearly 80 year old, I do not actively teach anymore but wishing I had your instructional talents. 73 WB0RSZ
What an Excellent explaination...👍👍👍👌
Thank you for your vidios! I'm already a general but it's good to refresh!
really good drawing and example of how it works. Thanks for sharing this one.
Those of us that have actually used NVIS have learned early on that an NVIS antenna is rarely more than 10 feet high. There are plenty of videos echoing the false information of 0.1 or 0.25 wavelength high. There are also plenty actually demonstrating true NVIS with their antenna 6 feet or even lower. NVIS was invented by the Germans for tactical purposes. Having a low antenna gets it down out of the noise and also makes it more difficult to DF. A low antenna is also much easier to deploy. All dipoles have an NVIS component. Being able to communicate via NVIS doesn't mean you have an actual NVIS setup.
Great job explaining
Very good refresher...thank you.
Another excellent video and explanation sir.
Noise of the cosmos. I am waiting on some alien QSL.
Hahaaa - you sound like some millennial coworkers that see antennas on my car and don't understand radio (do you talk to Mars??. Ha haaaa
Thanks for discussing this topic Dave. 73
Kudos for keeping it. NVIS was a critical military mode until satcoms came along, and it STILL fills a roll for those of us without satcoms.
I'm not sure about optimum NVIS height, but in the days before YT there was a lot of discussion about whether one yard or two was actually optimum height. FWIW.
I wonder if the league deleted it because "the book is just too fat now" and without it being on the question pool...snip!
As it turns out, it is covered in a different place, though not quite as thoroughly. The general class license manual is very much driven by the current set of test questions. That said, it's hard to find much written about NVIS.
Dave, great information for all hams, thanks for preserving it! K6DHP
My understanding is as a dipole gets lower to the ground it's impedance drops. With a real earth the impedance starts to go back up again. Is this extra impedance ground loss?. Also as you get closer to the ground I believe more signal is directed upwards. Is there an optimal height where the net vertical gain is lossed due to ground loss.
I assume a Dipole on the ground, even with a good swr has almost 100% ground loss. Is that correct, your just heating up the ground.
If a 40m dipole is 2m off the ground how do you work out how much is lossed to the ground?
Really surprised that NVIS was removed. Assume latest has more digital modes. Once again, top of the pops Dave, cheers n 73s A92GW AE1TP
As it turns out, it's covered in a different place. NVIS is very useful and is something that hams can learn more about and use to their advantage.
@@davecasler thx for taking the time to reply Dave. Yes I use NVIS while in Europe, i have great comms with Germany, Italy, Ukraine, Russia, on 20, n 40, of course Home Brew Dipole not so high.
But a great antenna config, i have worked DX is EndFed 1/2 Wave jn Inverted L config..
Best contact in that config was 20m Bulgaria to South Africa in early evening. 80 Watts.
You really do allot for the community, you have patience, treat every one with respect no matter what the query or scenario, a real gentlemen. Last question, are you still running the ALS500m ? Take Care Dave A92GW LZ/AE1TP
Hey - I got on 80M tonight..! HOW? I spent the best part of today putting up a FLAT Inverted-V (the ends about 10' AGL and the apex at 30'). That's NVIS. Great for nighttime armchair QSOs to about 250 miles radius - nondirectional.
Interezting video, wonder what the radiation pattern of the dipole would compare to a commercial or military grade NVIS antenna.
Electrons. Running wild.
I wonder why they pulled it. I thought NVIS was still widely popular (80m nets et. al.) and important enough to keep in the book.
As it turns out, it's covered in a different place although not in the same depth.
I get the sense most hams either inadvertently create nvis antennas due to less than ideal setups, and also think most hams want antennas for dx, perhaps this is why it was removed from newer edition
As it turns out, the NVIS section is covered a little bit in another section. And you're right. It's very hard to get low band antennas high enough. Maybe that's why verticals are so popular, because verticals have a much lower angle of radiation.
How about a inverted V? It doesn't go up or out but it does something near 45 degrees, depending on the slop.
For an inverted vee, the angle between the wires should be greater than 90 degrees ( a right angle). 135 degrees is nice.
Thanks Dave, for that excellent review.
I hear that NVIS is pretty popular right now in Cal. Due to the fires unfortunately.
73
out of state and inner state contacts are difficult to make from Cal. NVIS works for 100 - 1000 miles. That's why I'm using it from QRP to 100W max. power.
@@tomwoolston40 does it work well QRP?
How about on a car 🚙 mobile antenna ?
I want to know when is the best time of day to use 11m radio????
If you want long-distance, try early afternoon. Of course you can talk locally anytime.
NVIS has been really lousy for me over the past year with the current solar cycle. At best I can only get it to work at night time on 80m and nothing at all during the day.
Try 40 m during the day.
I wonder why NVIS was removed from the newer book? de W3DJS
As it turns out, it's covered in a different place although not in the same depth.
I couldn’t find the link to check the MUF. Could you send it to me, please?
www.spacew.com/www/fof2.html
Thank you very much.
73’s
Mark, N6AEB
1:26 - flat earthers get triggered.
Kind of wondering why they would omit something so important and basic as a discussion on NVIS.
Is the manual literally _only_ subjects mentioned in the current question pool, or something?
Yes, the manual only discusses topics that are in the question pool. However NVIS does show up later, but not in the depth that it did before.
You just proved flat Earthers wrong!!!
Lol
How? Flat Earthers do believe that the surface of the earth has mountains and curves and valleys, and in order to reach your body you have to reflect the wave through the dome
Curvature?? There is no curvature because the earth is flat as a pancake
As the ad stated, paraphrased, vote democrat and you will not get what you voted for, heartbreak is all you'll get
And yet I’ve voted democrat all my life and I’m still here. Voted for Reagan though.
Reuse and recycle lmfao.
Thank you David. Very Interesting!
4X4XM, Doron