NVIS Regional Radio Communications With Low-Slung Wire Antenna.
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- Опубліковано 21 жов 2024
- A low-slung wire antenna allows using Near-Vertical Incidence Skywave for regional communications. Contact Morse en Français and one using LSB to England, both on 80m.
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Great contact on 5W! Really enjoyed the video, and as always learned some valuable information. Merci Gil! 🙏🤠💥💥💥
Great video Gil! I have been able to work 80 meters NVIS SSB from inside a motel room! I used 100 watts into a 9:1 unun, and strung a 23 foot wire across the room about 8 feet from the ground! Can often work 100 to 300 miles away.
Great on a 23 foot wire!
Шикарный англичанин!
Высший класс - интеллигентный, внимательный, без суеты и понтов, и... с красивым английским!
Всем бы быть такими.
Gil, I found myself smiling throughout this video and realized how much I enjoy your videos, not only the content but also the atmosphere you create. It convinced me to join as a Patreon supporter. Thanks for your work!
Thank you very much! I am unemployed right now and it helps a great deal!
Outstanding video Gil. Putting this one up on the site.
👍👍👍
Thank you!
Good resources, thanks.
Outstanding demonstration of NVIS. Very nice work Gil
Thank you!
Using a copper coated steel wire is a great idea for long wires. This is a really cool experiment.
Thanks.
Hey Gil , another exceptional video, u and Julian are so prolific, sticking to the basics, you inspire, educate, entertain and befriend everyone who subscribes to yr channel. I love watching the fundamentals at play. Not seeing how the latest DMR gadget, hotspot integrates with another doodad,.. all the best and hope to work yr station one day NVIS from Bulgaria LZ/ AE1TP A92GW, cheers n 73s mate
Thank you! Bulgaria should work from here... If I spent more time on the air instead of making videos, LOL ;-) Let's hope..
Great video. Loved the footage and music choice for effect while you were hanging the wires. I was expecting to see Slender Man standing behind you ;) Keep up the great work! 73 de N1GF
I don't know how many times I'm working QRP and the other guy is running 400 watts (sometimes more). Cool demo of 80M NVIS. Also - the low antenna is indeed easier to deploy (easier than throwing a line over a tree, for example) and is typically quieter close to the ground too 👍. You have a very practical setup.
Same here... I just don't see why spend a fortune for an amp then waste so much electricity for something that doesn't bring that big an advantage...
Useful presentation!
4X4xm, Doron
Wow! This is one of the best videos I have seen on NVIS. I just had to subscribe.
Thanks!
When Winter is over, I will try this with a 71 ft wire and a 9:1 Unun.
trés bonne qualité de réception . propre c'est agréable . J'aime aussi beaucoup l'éclairage seul de l'équipement qui rend une ambiance trés " prepper "
et c'est tout simplement magnifique.
73 Gil
Merci! Le KX2 a d'excellent filtres et le DSP..
i totally agree about the code alpha bravo etc.
Hi Gil,
As I have said before I am a big fan of NVIS communication. So much so that I don't want to see its full capability sold short. Just like water boils at 212 degrees F is true at sea level; it is also true water boils at much lower temperatures when the atmospheric pressure is lower than at sea level. Likewise; you can almost always count on NVIS working on 80 and 40 meters because the upper atmosphere is, in a sense, nearly always opaque to those frequencies and rather than penetrating the atmosphere the signal is returned to earth. However as in water when boundary conditions change, any frequency that is capable of what is referred to as skipping will work in a NVIS mode if desired. If you look at websites that estimate or have measured the maximum frequency that skip will occur for on that particular day then any frequency under that upper limit is capable of NVIS for that specific day. So, my thrust of this little note is please don't sell frequencies higher than 7mhz short for use in NVIS situations. I have actually used NVIS with 11 meter radio during peak solar activity. Also, as a bit of a side issue, I have laid the antenna directly on the ground and then with trimming of the antenna have been able to acquire a NVIS situation for transmit with a very low SWR or reflected power.
Take care, love your channel.
Mike
Thanks. I will try it some time and mention that it's possible. We want reliability of course but that's another story...
Great video Gil, good job OM.
Thanks Joel :-)
Great video Gill.. A brilliant contact on such a low antenna (aerial?).. It just goes to show what works when you least expect it. 73 G7MJV
Thanks Andy.
Thanks Gil, another great video. That level of licence holder should be very embarrassed. I apologise on behalf of my countryman ! Keep up the good work 👍 Mike 6 India Echo Hotel 😎
Bah, no big deal. I think maybe some people try to sound cool, but it's confusing more than anything.
Thank you for the nice video. For SSB qso in NVIS style imo we have to use at least 20 W output, but for CW abt. 3 to 5 W works nice :) vy73, Dietmar, DL4HAO, QTH nr. Hamburg/Germany
Certainly 20W would have worked much better. I should have tried with my PRC-320.
I agree 100% on using the correct phonetic alphabet
NVIS is deffinitly something i want to practice with and have at my disposal should i need it for emergency communication. I just need to make some ham friends in my area to coordinate something. I love that all you have to do is string dipole or end fed a few feet off the ground. Great video.
I also enjoy being out at night as well. I always feel a little paranoid trying to operate out in public during the day if im in a busy area. Not that i dont enjoy talking to people about radio. I just dont necessarily want someone coming up to me randomly when im trying to accomplish something because they are curious about the weirdo stringing up a wire in a tree. If i were a bit more outgoing i would love to talk to strangers and potentially get them interested in amateur radio. I'm just too much of an introvert.
Indeed it is easier than it sounds. As to strangers walking by, so far I haven't had any trouble, just curious people, but you never know...
@@RadioPrepper I've definitely never encountered a stranger that was hostile luckily. But it depends on where your at in my area. Unfortunately if your In many of the city parks there are some questionable people that like to hang around and see if you have anything of value that you are leaving unattended.
Right... I do still expect someone to call the police on me some day... Oh well...
I live in an HOA, so experimentaton is imperative. I have a temporary 40 meter dipole set up in the yard. It is about 2.5 feet off the ground, definitely below 3 feet. The legs on the dipole are 30.1 feet per side, that is what it took to get an SWR of 1.2 or better on the general frequency range of 7.178 to 7.300 MHz. The antenna has been working great, didn't think it would get past Wyoming, Arizona, Colorado, & Nevada, but it has, and not bad, LOL.
I am in NE Utah and have had QSOs all the way to the east coast, signals of 2/1 to 4/4 , which is way better than the total ZERO I expected. Given the actual band conditions (not the good fair poor ratings found on the daily Solar Terrestial Data forecast) this antenna has done pretty good. I go on the OMISS 40 meter net in the evenings, and this is where I have been testing it.
This is a temporary setup, I hope to put it up to 35 feet later this week, waiting on a friend to bring the ladder we need to get up on the roof. I have been using this setup for the past 4 weeks and I am impressed with its performance. I would love to see what it will do on a day where the actual band conditions are good, but I am more anxious to get the antenna up and working under normal operating conditions. Given the HOA thing, I am happy that it works where it is now, not optimum, but it works, it is an alternative should the roof mount become an issue.
My elevation here is circa 6900 feet. The soil is conducive to plant growth, flowers, berries, apples, & vegetables, the soil retains moisture, but by 1 PM it is dry, and I set the sprinklers to go off at that time so the Kentucky Blue Grass stays green. When we dig here, it is mostly large rocks going down, the 8 FT copper ground rod became an angled one, no way to it drive straight down here. We are in the Rocky Mountains, LOL!
WW7GBA
Louis
Excellent! It is surprising how low you can go!
Outstanding work Gil. I use the HFlink .com World NVIS map for guidance and following this I find early mornings around 07.00 much better. Have just got up a 80m dipole about 15 feet above ground in an inverted V configuration. This looks promising but of course very hard to say where the signals are saturating as you don't get feedback from stations that can't hear you, unless you brake into a net for a group report. A further problem is other operators like your two contacts were not using NVIS configured antennas which I understand is necessary for best results.
What I would like to do is to replicate the US Marine Corps experiment with two humvees going north and south of a hub station and making NVIS transmissions every 25 miles. I believe they had success out to around 250 miles with antennas 4ft off the ground.
All I need is two humvees lol.
Many thanks Larry M3mpd.
Something else to buy, LOL. Mobile NVIS, that's another challenge.
Good video Gil. I have a similar antenna, 130ft. end fed in an inverted V. The peak is 20 and the ends are 10. On 80 I can work stations down the street or states away. Good fob with your 5 watts.
Thanks. I prefer 134ft for the CW portion...
Wow, excellent, and regional has to be taken in a broad sense, at least this night...
Indeed, I'd say up to 400 miles...
I think I would go back to using a small plastic box to contain the 49:1 transformer. Enjoyed the video.
Agreed; I already have two.
Hello Gil, nice video.
I have KX2 too and using Endfed antennas as well. Not really proficient (yet) in CW so mainly on SSB.
I was using KX2 in French Alps in winter with a random antenna, tuned with internal ATU, 2 to 3 meters high over the ground and it worked on 80m too. This is my favorite setup for SOTA activations on Reunion Island BTW.
Bonne continuation de Thomas F4HPX
Merci, et bon courage avec le Morse, ça vaut les efforts..
Fantastic Video Gil really enjoyed it, NVIS seems really cool 😎 though I’ve never tried it. And at least G0-Achieving Wasted Vocabulary🤪- The phonetic Luddite appreciated your skill sets. Gil you Rock. 👍🏼👍🏼👍🏼
Thank you!
Very interesting!
I agree with you about wishing people would use the universal phonetics.
Great video all to gether.
73s
Thanks.
You need to be the sailing radio prepper channel
Hopefully I'll get a new boat and will be maritime-mobile again!
Halloween music =) A little QSB on both of those QSOs but well done. NVIS is a very nice technique that particular antenna can be used at 2 meters but an optimal setup is about one eight of a wave length. So 10 meters on 80, 5 meters on 40. That seems to give you the most gain upwards whilst still reducing vertically polarized local noise. I've had exceptional results with antennas that were set up that way and my QRP rigs. W4MHz ;) I will just add that you will do better if you support the center of your end fed at about 1/8 lambda and keep the ends about one or two meters off the ground. That configuration is very effective and is in common use in many armies around the world a counterpoise will give you about 3 dB additional gain as well.
Indeed. And I thought the music was appropriate ;-)
Gil, you might consider laying down on the ground a 5% longer wire than the 1/2 wl right under the antenna when it is in straight line, could maybe give some enhancement?
Oh yes, three parallel ones is even better!
We have been unsuccessful at using NVIS antennas for local communications on 40 meters. My antenna is basically between a dipole and an inverted V. The balun is about 15 feet (4.57 meters) above the ground and one end is about 2 feet (.6 meters) & the other about 4 feet (1.2 meters) above the ground. I can make contacts with stations more than 400km away but not any locally.
You might want to try with a horizontal antenna without dropping ends...
@@RadioPrepper Ok thank you for the advice.
Bonjour,
One question, you use an inhabitual 49/1 balun , I guess that you feed your antenna at a end. As you have plenty space and a full half length , at 4 feet hight , could this antenna be feed on the half with an ordinary balun 1/1 ? Or Im wrong assuming that the impedance of an antenna is low when near the ground ?
Hi, I find it more convenient to feed it at the end. The impedance doesn't change much, though I have not tried it higher than 20ft horizontally.
@@RadioPrepper Do you say that feeding it as a dipole was almost the same with a wire 4 feet high ?
I search if the impedance is lower or higher when the antenna is low , but i dont find an answer..
No. I'll have to look into that... I just think the difference is not great with height changes below 20ft for the end-fed.
@@RadioPrepper Sure tht's the balun which is not the same ..😊
Thank you for the demonstration. I need to reach 25-50 miles , over mountains for my group emergency communications system. There is one or two repeaters for 2 meters, but we need a system that does not rely on the repeaters. Can I use NVIS for contacts as close as 25 miles?
It should work.
@@RadioPrepper Merci! I am studying for the US General license, and shopping for HF gear. I will try the NVIS... I have plenty of room on my land for wire antennas.
You might want to post your results on radiopreppers.com...
Nice demo on NVIS
Thanks.
Great video ... I hope it was not too cold. 73 DE S58F ERIC
I slept well :-)
Yes the resin around the core seems to me to bugger them.
Maybe, but I would not have thought so...
Hello @@RadioPrepper and thank you, there is some conjecture between rosin and epoxy, the only personal experience is I covered a balun 4:1 with epoxy and it did lift the swr unsatisfactorily not greatly but I would not use it. Here in Australia with the Flying Doctor network the antennas they supply have baluns encased in a hard epoxy/rosin and it is not clear, like material, it is impossible to get the material out without destroying it. I also have coated home made copper 50mm dia copper coils with rosin around the 14 to 20 uHy mark with out any difference to the inductance of the coil. Sorry, that's measuring the coil after making and coating to let dry, I now cut and use spacers out of PE bread board, a lot better i can change the pitch if i want. Thank you for your videos. All good, all of them. Dennis Bauer VK4JDJ 73
How did you determine the need for a 49:1 xformer specifically vs, say, a 9:1?
Because my wire is a half-wave length, very high impedence... A 9:1 would be for a "random" wire, other than a half-wave...
How did you arrive at the value of 49?
2 turns primary and 14 turns total is a 7:1 ratio, 7 squared is 49.
Thanks! Do you have a recommended reference for such calculations?
Not really, just stuff I picked up along the way. Best way is to just experiment and browse Internet resources...
Good video.
Thanks.
Would a mag loop be any good for NVIS?
Yes, both NVIS and DX. I do think most commercial loops are too small though. A 5m perimeter seems ideal to me.
I've seen those... The loop folds into the roof rack.
Bonjour prepper
Bonjour David.
I am getting 100/150 km NVIS on 80m ssb and cw doing SOTA working my local vk5 chasers when i go activating during daylight . Sometimes with lots of bush on the summit the 80m extensions to my dipole lay on top of the bushes and it still works fb. Sorry there is still interaction with the resin balun its looks too good not to work hi.
Yep that's NVIS for sure..
Nice video Gil de KE0RFZ. 73
Please make a video about a "wonder EH antenna''worth to build.My call sing YO2MFU
I am not sure there is one worth building...
I amazed how the English can never pronounce your name properly, Gil! It's really not that hard for the English voice! (I well remember French lessons at age 11, at my English school, perfecting the pronunciation of phrases like "je m'appelle", to the satisfaction of the teacher!)
Indeed. I tell the to pronounce it like "jeel" without the "D" sound.
The best chnl on u tube 73 kg6mn
Thank you!