I've been a ham for over 40 years, but never has there been such a prolonged period of such poor propagation. This has been especially the case over the past six months or so, and they continue to deteriorate.

What could possibly be the cause?

This is taking into account information from sites such as Spaceweather and the sites linked to from this page on my site. Even when solar conditions seem to be favorable for good band conditions, the bands are terrible.

Sure, there's solar flares, CMEs, and other events that typically make the bands go "dead". But those effects have been taken into account.

NOT caused by increased man-made noise

In many locations, man-made noise is a factor. But I asked this question from the viewpoint of hams living in quiet areas; my location is almost noise-free, and there are times when my s-meter is zero even with the preamp on. This is about the signal levels dropping.

This image below is from K5BIZ's website. The network of receivers feeding data to it from K5BIZ's beacons is the most reliable indicator of real-time HF band conditions we've found. The majority of the time, the arrows on each band graph there have mostly been in the red areas of the the graphs for most of these bands like below, and they closely indicate what we hear on the bands. It wasn't always like this.

I know we are near the solar minimum, but it certainly seems that something else is at play. Many other hams concur. What could it be?


Typical poor band conditions


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    Ditto -- this is worse then the last sunspot low. I usually have my radio listening on the 20-meter beacons at 14.1 MHz mostly because the white-noise is good background. On a good year, I can hear all North American Beacons plus Hawaii. Today, for example, just a few moments ago, all I could hear was Southern California beacon (W6WX). Here is a good link to follow for HF beacons: ncdxf.org/beacon. FYI, my QTH is near Seattle, WA. – K7PEH Jul 24 '17 at 14:27
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    I have been a ham for over 50 years and I tend to agree with Mike. It seems to me that the present solar cycle has shown very few of the attributes that make hams happy. This is especially true for the lower (160 & 80M) bands. Yes there has been propagation but the general quality of the signal appears to be down quite a bit. I recently read something on one of the government sites that suggested scientists believe the sunspots from ol' Sol are getting fewer and farther between and it went on to say they thought that sometime in the distant future sunspots would go away all together. ... – Poe Aug 18 '17 at 23:09
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    Interesting article: Solar Minimum surprisingly constant. astrowatch.net/2017/11/solar-minimum-surprisingly-constant.html – SDsolar Nov 19 '17 at 6:35
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    What rigorous data are there to indicate sustained poor conditions on HF, versus other explanations for having no one to talk to (like a possibly declining number of active CW operators)? – Phil Frost - W8II Jul 10 at 0:00
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    I've made a few cursory searches, but unfortunately I can't find any controlled propagation study that goes back more than a few months. It would be great if the data from bandconditions.com were archived over many years, but I've not found it yet. – Phil Frost - W8II Jul 13 at 17:12

There's no real magic, it's just the signal to noise ratio. If you're certain that the noise floor hasn't changed then the signal propagation has, and vice-versa.

Any number of upper atmosphere hypotheses can lead to a lower charge density which means a lower reflection coefficient resulting in a weak bounce and lousy HF propagation. As you've pointed out at sunspot minimum the density of charged particles passing the earth is lower and that means less charge separation and so on.

I don't think either halogenated hydrocarbons or rising CO2 levels or global warming make a viable whipping boy for this one. They don't have enough effect in the right layers AKAIK. If you want to blame one of those anyway then it looks to be a long wait for better conditions.

I don't think we can blame this on North Korea's rocket testing, IIRC the ionosphere hole from the launch vehicle motor's exhaust fill back up in around 15 minutes. Aw, heck, sure we can... just hypothesize something bizarre in their fuel.

So, that leaves volcanism, meteor showers, and Santa Claus to consider... moving right along...

If that's not it then ... the noise floor. A few billion poorly sheilded digital noise sources and the noise pedestal from cell phone LO's and IFs can't be helping. The rising average utility transmission and distribution voltage coupled with diminishing insulator maintainance may be another source of broadband noise. Someone's bound to have some noise data somewhere...

  • Historically, near solar minimums the upper bands deteriorate while conditions improve on 80 and 160. My point is that all those bands remain poor and the signal levels are much lower. As you said, there is indeed an overall increase in RFI from such devices as switching power supplies. However, in many locations (mine included) we hear little of that. Something else is definitely at play here. – Mike Waters Aug 15 '17 at 23:04

After listening to the increased noise level on 20M, and its direction, I observe that the noise has a man-made character, varies greatly over short periods, and always peaks with the peak direction of propagation, mostly NE to Europe.

That's what got me googling and to this page with the same suspicion as Noah's - that man-made RFI is artificially raising the propagated noise level.

This is something fundamentally different than what we used to consider a local problem, and seems like a plausible explanation for the really awful state of 14 MHz.

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    In many locations, man-made noise is a factor, yes. But I asked that question from the viewpoint of hams living in quiet areas. My location is almost noise-free. There are times when my s-meter is zero even with the preamp on. Please see my comment above. This is about the signal levels dropping. – Mike Waters Sep 3 '17 at 14:57
  • My comment is that noise is being propagated. I believe I was clear about that. Therefore it doesn't matter where you live. – Bob Crowley Dec 12 '17 at 0:28
  • @Bob-Crowly I think that we are talking about two different things here. I fully agree that more man-made noise is being propagated. And I can sometimes hear an increase from that when I listen towards the densely-populated areas to my NE. But compared to the very large decrease in the signal levels, that increase is minimal. – Mike Waters Dec 15 '17 at 20:43

It's pretty clear that we've reached the ~10.7-year solar cycle minimum in the midst of a low part of the ~87-year Gleissberg Cycle. See this explanation from Wikipedia.

Occam's Razor points toward this relatively simple (though unfortunate for us hams) scientific explanation rather than other explanations.

As usual, some hams are responding to this problem by innovating with new weak-signal methods like FT8.

  • We won't see it, but like clockwork, the earth is headed into another ice age. – w5dxp Nov 14 at 13:17
up vote -2 down vote
+150

Bands were down, for the first several months figured it was temporary, even though repeatedly Space Weather had no proton showers or other anomalies to explain it. Been a ham for over 50 years, never remember anything like it.

I've begun to suspect some sort of human activity is poisoning the ionosphere. Perhaps a state actor is doing it deliberately for some nefarious purpose, or the proliferation of metallic space junk is knocking out the charged particles up there by some as yet unknown mechanism, or perhaps the fluorocarbon induced ionospheric holes have hit a critical size.

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    Hi, and welcome to hamSE! Did you mean the ozone layer? Is that part of the ionosphere? Regardless, I thought the ozone layer holes had somewhat "healed" due the the laws mandating the phasing out of chlorofluorocarbons. – Mike Waters Jan 8 at 21:36
  • Just found an interesting article on point called "Approaching ‘grand solar minimum’ could cause global cooling" wattsupwiththat.com/2018/03/18/… - I very rarely hear anything on 20 Meters right now and can't wait for it to get the mojo back. – SDsolar Mar 19 at 17:23
  • I fully agree that it is human activity. There are two possibilities. I have some sound scientific information that I'll share here, if I ever get the time. :-) – Mike Waters Jul 14 at 22:43
  • This is the latest. Whoever downvoted this, please read it. :-) – Mike Waters Sep 15 at 17:45
  • Hi @SDsolar I thought we established here that the solar minimum can only go so low? The link in my comment above mentions warming and not cooling. – Mike Waters Sep 15 at 17:49

Heard another possibility on the "street". The proliferation of 'space junk' may have something to do with the singularity of the recent HF propagation decline. My recollection of a recent score keeper's reports is that there are 166 million pieces of man made stuff in orbit larger than 1 mm (or is it 1 cm?) weighing of the order of 8000 tons, including 4000 satellites and pieces from 500 collisions. Could that stuff be affecting the ionosphere?

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    If anything, it would allow signals to reflect down, improving propagation. However, when you consider the percentage of sky covered up by space debris (hint: almost none, since you can't see any effects of the debris from the ground; astronomy is basically unaffected), I'd say the effect is likely to be immeasurably small. – Jim MacKenzie VE5EV Oct 23 at 22:50

A lot has to do with fewer hams out there and many that lack ability or motivation to setup antennas that work. Just something I have noticed over the years...laziness? Jim

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    I am not convinced that the numbers back this up – Scott Earle Aug 21 at 6:58

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