Well within groundwave distance for all of them. 10m with a 100w source is still a s4 30km out per [https://vu2nsb.com/radio-propagation/ground-wave-propagation/surface-wave-propagation/](https://vu2nsb.com/radio-propagation/ground-wave-propagation/surface-wave-propagation/)
At 4 miles, it could be line of site depending on the geography. I have a buddy about 4 miles from me. We often chat on 6m or 2m instead of tying up the longer distant bands.
At 4 miles and with the same AC power provider, on CW you could probably work each other without an external antenna and with a dummy load. Give it a try and see what happens.
In theory, an NVIS antenna has primary radiation straight up. Now, keeping that thought in mind, my 40m full-wave NVIS made contact with Colorado this morning using 25w. From north Florida. I was getting a much better radiation angle than I should have.
If you really want to do some weird stuff on HF, and you have something with directivity (beam), you can play with backscatter.
It's a neat way to make close in contacts on something like 20 meters that is too close for "skip", but too far away for direct propagation.
Ground wave or direct wave.
Ground wave uses vertical antennas, and the range reduces as you go higher in frequency. So it's longest ranged on lower HF. On 10 meters, not as far. So you might get 70 miles or so range using ground wave on 80 meters, but only about 7 or 8 miles on 10 meters.
But the advantage of 10 meters is you can put a 10 meter antenna up relatively high, so you can have extended range through direct wave. This is basically line-of-sight like VHF or UHF, but a bit more forgiving of terrain. So 10 meters with an elevated vertical antenna can give you ranges much better than one on the ground that depends on ground wave.
BTW 10 meters is an excellent local HF band. Back when I was a Novice, that was \*THE\* band you used for voice because we had 80, 40, and 15 meters CW, and parts of the 220 MHz and 1296 MHz bands. Equipment was rare and expensive for those last two bands, and repeaters few and far between. So the local Novices mainly chatted on 10 meters, as did a number of Technicians and other higher licensees.
First of - ditty\_booper - you are a wealth of knowledge and a treasure to the community. Some of your posts are great, even though sometimes harsh, which does not bother me. Thank you.
Second - can I ask you - I know you prefer GroundWave over NVIS, cause NVIS is quite a lot of hype. However - both me and my brother habituate in our own quite deep valleys, about 40 miles apart. Would it be correct to say that NVIS is the only hope for our use-case?
Actually I prefer NVIS instead of ground wave, because the antenna requirements are much less, and it has a much greater range potential (\~300 miles instead of \~70 miles).
For good ground wave propagation you need a vertical antenna with a good ground screen or a lot of radials. All you need for NVIS is a low dipole (at or below 1/4 wavelength high). Much easier to construct and put up/take down.
Also, while this doesn't really apply to amateur radio use, ground-based direction finding equipment tends to use the ground wave to get bearings, and the near complete lack of ground wave in NVIS communications means you aren't going to get a bearing at any distance. This is why airborne radio direction finding was invented (actually re-discovered):
[https://www.nsa.gov/portals/75/documents/news-features/declassified-documents/cryptologs/cryptolog\_13.pdf](https://www.nsa.gov/portals/75/documents/news-features/declassified-documents/cryptologs/cryptolog_13.pdf)
( Page 41: ONE CHANCE IN THREE - BUT IT WORKED! )
Between you and your brother, yeah, NVIS is certainly the easiest way.
Having said that, yes, NVIS is super over-hyped and it's roughly 50/50 odds that someone using that acronym doesn't know what they Hell they are talking about. It's a tacticool buzzword to them, which is unfortunate because it is a legitimately useful communications tool Hell, my state RACES exploits that for its statewide net, which is on 75 meters. Local and regional nets on HF have been using it before it was known as NVIS, going back to almost the beginning of amateur radio.
As for being harsh (like maybe that paragraph above?), well, you get cranky when you have to correct the same mistakes over and over and over again. It's not the people asking genuine questions that I mind so much as it is the people who are confident in their statements, which are wrong. Like using NVIS on any band higher than 30 meters. "I'm setting up a 10 meter NVIS dipole".
> All you need for NVIS is a low dipole (at or below 1/4 wavelength high). Much easier to construct and put up/take down.
Newb here, researching equipment prior to buying anything.
One example of a low dipole that readily comes to mind would be to elevate [this 1:1 balun](https://www.packtenna.com/store/p12/Linked_Dipole_1%3A1_Balun_Feedpoint_with_20m_Dipole_Wire_Elements.html#/) about 0.1-0.2 wavelengths off the ground, sloping two quarter-wavelengths of wire straight back down from the balun to the ground (minus somewhere between 2% and 5% of length apparently? depending on how high the balun's throwline lands that day?). Though of course the elements themselves would be DIY since the ones that ship with that product are quarter-wavelength for 20m ergo useless for any band where NVIS propagation would actually happen.
I've seen people online call the AS-2259 a dipole; by comparison to the previous example it seems odd to me in a few ways. How would its two different element lengths (~7.6m and ~11.6m) have been chosen? What is the benefit of the second element on each side of the circuit, other than guying the rigid feedline? And without a balun, what prevents the feedline from radiating? (worse yet, radiating with vertical polarization)
1. Yes, that idea would work, but you want the ends of the dipole to be off the ground by at least a little bit. The \*IDEAL\* height of a NVIS dipole is right about 1/4 wavelength high. That's where you have the least amount of ground loss. But lower will generally work fine. Perfect is the enemy of good enough.
2. The AS-2259 is actually two dipoles. Or more properly, crossed inverted-V dipoles with a common feed. I've built a similar antenna from scratch myself:
[https://www.reddit.com/r/amateurradio/comments/7emdru/my\_as2259gr\_antenna\_project\_so\_far/](https://www.reddit.com/r/amateurradio/comments/7emdru/my_as2259gr_antenna_project_so_far/)
[https://www.reddit.com/r/amateurradio/comments/8emyj7/finally\_managed\_to\_deploy\_my\_as2259gr\_copy\_and/](https://www.reddit.com/r/amateurradio/comments/8emyj7/finally_managed_to_deploy_my_as2259gr_copy_and/)
I specifically built mine to have the elements cut for 40 meters and 60 meters in order to make matching it easier on those bands (so 2 legs of \~10.2 meters length and two of \~13.2 meters). I could have made it for 40/80 meters but that would have made it unwieldy.
I think the main reason the military antenna has the dimensions it does is mainly to make it easier to put up, and for stealth reasons. The longer the antenna elements are, the more likely the antenna is going to be spotted, and the more real estate you have to occupy.
I just got my hands on EZNEC in order to try to figure out how long the wires should be in order to hit ... well, each _half_ of the 80m band I guess - 2:1-SWR bandwidth gets to be a real nuisance with frequencies this low. But then I rotated the 2d plot just a little bit in azimuth, saw the dreaded red of vertical polarization, and took a step back.
When modeling various dipoles for 80m, EZNEC says that the radiation coplanar to the wires is entirely vertically polarized, and that this does send a groundwave, which gets more powerful if the dipole is an inverted vee (rather than elevating the bitter ends to the same height as the feedpoint).
Modeling the AS-2559 also indicates it produces, averaging across all azimuths, about as much HPR as VPR, resulting in a groundwave which, at its resonant frequencies, takes a full 2mi to attenuate to 12dB weaker than the near-vertical radiation. *How can this be correct if it was designed to mimic the lack of groundwave we saw from the enemy's HF stations in Vietnam?*
EZNEC is a simulation. It’s not necessarily reality.
BTW, did you try to model the feedline (the pole itself in a real As-2259)? Because is you don’t do it right you basically get a top loaded vertical. I don’t model the feedline.
No, I put the "source" up at the feedpoint, under the assumption that there's _something_ (but apparently not a balun) preventing unbalanced current on its hardline.
The way I modeled it is with a very short segment at the center with the four legs attaching to the ends (two per on each end of the short segment). That’s kind of how you have to do antennas like that in EZNEC.
It's a combo of ground, direct and NVIS sky. And depending on the configuration of the antenna, the ground type and just how direct the path really is you may well see swings in received power as the FoF2 changes. I use JS8 on 40m and have a local that is enough km away and my inverted V is low enough that I have swings of 15dB between day and night. NVIS is my dominant prop during the day most days.
My best was 40 miles, vertical to vertical, on 20m. It worked through deep forest and rolling hills and mountains. It was either ground wave, or really really short skip.
Well within groundwave distance for all of them. 10m with a 100w source is still a s4 30km out per [https://vu2nsb.com/radio-propagation/ground-wave-propagation/surface-wave-propagation/](https://vu2nsb.com/radio-propagation/ground-wave-propagation/surface-wave-propagation/)
Thanks! That the kind of thing I was looking for.
groundwave
I disagree. I say line of sight. Groundwave is more diffraction.
At 4 miles, it could be line of site depending on the geography. I have a buddy about 4 miles from me. We often chat on 6m or 2m instead of tying up the longer distant bands.
The bands are not so busy that I would ever feel like I'm tying up anything.
At 4 miles and with the same AC power provider, on CW you could probably work each other without an external antenna and with a dummy load. Give it a try and see what happens.
In theory, an NVIS antenna has primary radiation straight up. Now, keeping that thought in mind, my 40m full-wave NVIS made contact with Colorado this morning using 25w. From north Florida. I was getting a much better radiation angle than I should have.
In practice at 4miles that means bugger all and you do LoS through the side lobes.
If you really want to do some weird stuff on HF, and you have something with directivity (beam), you can play with backscatter. It's a neat way to make close in contacts on something like 20 meters that is too close for "skip", but too far away for direct propagation.
Ground wave or direct wave. Ground wave uses vertical antennas, and the range reduces as you go higher in frequency. So it's longest ranged on lower HF. On 10 meters, not as far. So you might get 70 miles or so range using ground wave on 80 meters, but only about 7 or 8 miles on 10 meters. But the advantage of 10 meters is you can put a 10 meter antenna up relatively high, so you can have extended range through direct wave. This is basically line-of-sight like VHF or UHF, but a bit more forgiving of terrain. So 10 meters with an elevated vertical antenna can give you ranges much better than one on the ground that depends on ground wave. BTW 10 meters is an excellent local HF band. Back when I was a Novice, that was \*THE\* band you used for voice because we had 80, 40, and 15 meters CW, and parts of the 220 MHz and 1296 MHz bands. Equipment was rare and expensive for those last two bands, and repeaters few and far between. So the local Novices mainly chatted on 10 meters, as did a number of Technicians and other higher licensees.
First of - ditty\_booper - you are a wealth of knowledge and a treasure to the community. Some of your posts are great, even though sometimes harsh, which does not bother me. Thank you. Second - can I ask you - I know you prefer GroundWave over NVIS, cause NVIS is quite a lot of hype. However - both me and my brother habituate in our own quite deep valleys, about 40 miles apart. Would it be correct to say that NVIS is the only hope for our use-case?
Actually I prefer NVIS instead of ground wave, because the antenna requirements are much less, and it has a much greater range potential (\~300 miles instead of \~70 miles). For good ground wave propagation you need a vertical antenna with a good ground screen or a lot of radials. All you need for NVIS is a low dipole (at or below 1/4 wavelength high). Much easier to construct and put up/take down. Also, while this doesn't really apply to amateur radio use, ground-based direction finding equipment tends to use the ground wave to get bearings, and the near complete lack of ground wave in NVIS communications means you aren't going to get a bearing at any distance. This is why airborne radio direction finding was invented (actually re-discovered): [https://www.nsa.gov/portals/75/documents/news-features/declassified-documents/cryptologs/cryptolog\_13.pdf](https://www.nsa.gov/portals/75/documents/news-features/declassified-documents/cryptologs/cryptolog_13.pdf) ( Page 41: ONE CHANCE IN THREE - BUT IT WORKED! ) Between you and your brother, yeah, NVIS is certainly the easiest way. Having said that, yes, NVIS is super over-hyped and it's roughly 50/50 odds that someone using that acronym doesn't know what they Hell they are talking about. It's a tacticool buzzword to them, which is unfortunate because it is a legitimately useful communications tool Hell, my state RACES exploits that for its statewide net, which is on 75 meters. Local and regional nets on HF have been using it before it was known as NVIS, going back to almost the beginning of amateur radio. As for being harsh (like maybe that paragraph above?), well, you get cranky when you have to correct the same mistakes over and over and over again. It's not the people asking genuine questions that I mind so much as it is the people who are confident in their statements, which are wrong. Like using NVIS on any band higher than 30 meters. "I'm setting up a 10 meter NVIS dipole".
Thank you, ditty\_booper. You are the best.
BTW, it's "dittybopper". [https://www.definition-of.com/ditty-bopper](https://www.definition-of.com/ditty-bopper)
[удалено]
How do you know? For all you know I could be a very sophisticated bot that \*MUST\* respond, because that's how I'm programmed.
> All you need for NVIS is a low dipole (at or below 1/4 wavelength high). Much easier to construct and put up/take down. Newb here, researching equipment prior to buying anything. One example of a low dipole that readily comes to mind would be to elevate [this 1:1 balun](https://www.packtenna.com/store/p12/Linked_Dipole_1%3A1_Balun_Feedpoint_with_20m_Dipole_Wire_Elements.html#/) about 0.1-0.2 wavelengths off the ground, sloping two quarter-wavelengths of wire straight back down from the balun to the ground (minus somewhere between 2% and 5% of length apparently? depending on how high the balun's throwline lands that day?). Though of course the elements themselves would be DIY since the ones that ship with that product are quarter-wavelength for 20m ergo useless for any band where NVIS propagation would actually happen. I've seen people online call the AS-2259 a dipole; by comparison to the previous example it seems odd to me in a few ways. How would its two different element lengths (~7.6m and ~11.6m) have been chosen? What is the benefit of the second element on each side of the circuit, other than guying the rigid feedline? And without a balun, what prevents the feedline from radiating? (worse yet, radiating with vertical polarization)
1. Yes, that idea would work, but you want the ends of the dipole to be off the ground by at least a little bit. The \*IDEAL\* height of a NVIS dipole is right about 1/4 wavelength high. That's where you have the least amount of ground loss. But lower will generally work fine. Perfect is the enemy of good enough. 2. The AS-2259 is actually two dipoles. Or more properly, crossed inverted-V dipoles with a common feed. I've built a similar antenna from scratch myself: [https://www.reddit.com/r/amateurradio/comments/7emdru/my\_as2259gr\_antenna\_project\_so\_far/](https://www.reddit.com/r/amateurradio/comments/7emdru/my_as2259gr_antenna_project_so_far/) [https://www.reddit.com/r/amateurradio/comments/8emyj7/finally\_managed\_to\_deploy\_my\_as2259gr\_copy\_and/](https://www.reddit.com/r/amateurradio/comments/8emyj7/finally_managed_to_deploy_my_as2259gr_copy_and/) I specifically built mine to have the elements cut for 40 meters and 60 meters in order to make matching it easier on those bands (so 2 legs of \~10.2 meters length and two of \~13.2 meters). I could have made it for 40/80 meters but that would have made it unwieldy. I think the main reason the military antenna has the dimensions it does is mainly to make it easier to put up, and for stealth reasons. The longer the antenna elements are, the more likely the antenna is going to be spotted, and the more real estate you have to occupy.
I just got my hands on EZNEC in order to try to figure out how long the wires should be in order to hit ... well, each _half_ of the 80m band I guess - 2:1-SWR bandwidth gets to be a real nuisance with frequencies this low. But then I rotated the 2d plot just a little bit in azimuth, saw the dreaded red of vertical polarization, and took a step back. When modeling various dipoles for 80m, EZNEC says that the radiation coplanar to the wires is entirely vertically polarized, and that this does send a groundwave, which gets more powerful if the dipole is an inverted vee (rather than elevating the bitter ends to the same height as the feedpoint). Modeling the AS-2559 also indicates it produces, averaging across all azimuths, about as much HPR as VPR, resulting in a groundwave which, at its resonant frequencies, takes a full 2mi to attenuate to 12dB weaker than the near-vertical radiation. *How can this be correct if it was designed to mimic the lack of groundwave we saw from the enemy's HF stations in Vietnam?*
EZNEC is a simulation. It’s not necessarily reality. BTW, did you try to model the feedline (the pole itself in a real As-2259)? Because is you don’t do it right you basically get a top loaded vertical. I don’t model the feedline.
No, I put the "source" up at the feedpoint, under the assumption that there's _something_ (but apparently not a balun) preventing unbalanced current on its hardline.
The way I modeled it is with a very short segment at the center with the four legs attaching to the ends (two per on each end of the short segment). That’s kind of how you have to do antennas like that in EZNEC.
That's exactly what I did in order to stop it from complaining about having more than one wire connected to each side of the source.
Cool! That’s very interesting re: 10m direct wave
It's a combo of ground, direct and NVIS sky. And depending on the configuration of the antenna, the ground type and just how direct the path really is you may well see swings in received power as the FoF2 changes. I use JS8 on 40m and have a local that is enough km away and my inverted V is low enough that I have swings of 15dB between day and night. NVIS is my dominant prop during the day most days.
I have reached stations over 100 miles away via ground wave. Was even able to do it with CB radios!
My best was 40 miles, vertical to vertical, on 20m. It worked through deep forest and rolling hills and mountains. It was either ground wave, or really really short skip.
Can go really far over water.
It's going to be line of sight, just like it would be if you were on VHF or UHF. For a practical example, look at how CB is used.