Polar Non-Summer Mesospheric Echoes, and backscatter signals.

Interesting to see the mid-latitude winter version of PMSE break out weakly above Wales this afternoon.

Conditions have been mostly quite tough on 12m today, relative to the past week or two, due to the quiet geomagnetic conditions.  But there are periods of good, if weak DX, notably to ZS and PY.  Signals from EA8 are extremely strong, with German and Belgian stations showing a pronounced backscatter reception path. 

The backscatter is worth recording: OS8A (see video) was coming in at -18 to -7dB when I was beaming towards him, but came in at +9dB when I was beaming 220, out into the southern Atlantic.  Similarly, nearly an hour after sunset here, EA9ACD was -17dB in a dying band when beaming 220 degrees, but entirely undetectable on a direct beaming path to him.

Whether or not this is related to the winter echoes is an open question.  There are no signs of the unusual bursts much-discussed on this page in recent months.

Vertical radar profile above Aberystwyth, Wales today.  Vertical lines are data glitches, real echoes are the blue patches from around 08UT onwards at 75-80km altitude.

The precise cause of winter echoes is not understood.  Infrasound from rough seas propagating into the mesosphere is one idea.

Looking back at the past month's MAARSY data from 70 degrees north, there have been quite a number of PMWE breakouts, notably on the 24th October, where the returns were strong and long-lived (top plot; lower plot is lower atmosphere and irrelevant to this subject):

Data courtesy IAP/MAARSY.

In other news, a bloody great big sunspot group has just emerged into view.  More fun to come on the bands, I think!

Courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.

Half Rhombic Time!

Well, the weather has finally stabilised a bit this week, allowing some thoughts to return to antenna experimentation.

Very much encouraged by the spectacular results over the past year or so at the coast, I decided to experiment with a vertical half rhombic antenna - an antenna type that doesn't get a lot of attention.

The basic expectation is that the real half of the antenna will, at the coast, have an extremely good image in the ground, and thus give near full-rhombic performance - with the added benefit of gain from very low angle radiation.

Basic idea of the half rhombic, but using a counterpoise wire.  I will start without such a wire, using a direct earth connection at each end instead.

 

The rhombic can be bidirectional when non-terminated, or unidirectional when terminated.  As it happens, a very ambiguous and incomplete set of results with a Vee-beam last year meant I already have some high power resistors to try with the new half rhombic.

I figured that a wire length of about 34m worked out at roughly 4 half wavelengths total wire at 18MHz, 5 half wavelengths at 21MHz (an odd number, which won't work, according to some texts), and 6 half wavelengths at 24MHz.  

A 4:1 balun transition from balanced line to a short coax-to-rig connection should hopefully allow a good match at 18 and 24MHz wavelengths, and also see what happens on the odd wavelength multiple at 21MHz.  

The 'outer' of the feedline will be connected to a simple copper ground stake, as will the terminated end.  If this fails, I'll have a go at a counterpoise.  The near-perfect beach ground should render this redundant, though.

The plan is now to set up the antenna one early morning on 18MHz at the beach, with the terminated end aimed to the East.

We'll see how it goes!  Update: here's how it went initially.

Quiet conditions again

KP reached only a maximum 2 overnight, bringing a very subdued 14MHz WSPR signal from VK3QN, but which continued again to be received almost until lunchtime here (presumably, this post-09UT signal is radiation from the back of the large, 12-ele array making it via shortpath to Europe):

The 20m band closed very firmly here at 19:50UT (last spot G4UGD), with all DX lost slightly earlier, at 19:20UT (8P9GH).

Then, from 00:22UT to 01:50UT, 2E0XLG appeared at very weak SNR, presumably linked to a brief, sharp northerly swing in the geomagnetic field:

14MHz WSPR reception of 2E0XLG (0.2W) by MW1CFN, 2020 October 03-04.  Long horizontal lines indicate periods of non-reception.

Quieter conditions bring unusual reception.

After a few dyas of geomagentic disturbance, the field was reasonably quiet overnight, but with some low-level 'ringing' at very high latitudes during most of the morning.

Even for quieter conditions, the 14MHz WSPR signal from long path Europe-beaming VK3QN was extremely unusual, continuing into the late morning period today.  Normally, after a brief long path peak, he disappears about 08UT or so.  The grey rectangle indicates a period where the signal was not received:

Z component magnetometrey 02-03/11/2020.  TGO.

Lab599 suffer delivery delays

The ongoing, already delayed story of the Lab599 TX-500 transceiver from Russia seems to be hitting the buffers at the moment (accessed 09:00UT, 03/11/2020):

We have to accept that running even the best business these days is tough going, and so Lab599 can hardly be criticised for the world's current problems.  

The question for Lab599 at the moment is whether Icom's simultaneous launch of the IC-705 will effectively destroy the TX-500's chances of gaining a market foothold.  

Of course, the TX-500 is a very different beast to the IC-705, and that fact already filters out the 'boys who want every bell and whistle' from those who just want a simple, tough, capable HF-only rig.  So I think that, if all goes well next year, the TX-500 could still gather a very strong following amongst the ham community.

Still very few meaningful video updates about the TX-500's technical performance in the real world, other than what appears to be a Lab599-produced, side-by-side comparison of, well, only receive audio, to be honest, between the TX-500 and the KX-3.  Whilst the TX-500 is good, the KX-3 certainly sounds a lot better to my ears on both SSB and CW.  That, and the fact that the KX3, unlike the TX-500, is readily available in most countries.

 

One of two, 5dB up.

Happy to be one of only two in the 17-18UT period getting across from anywhere outside the US to AI6VN/KH6 this evening again with the vertical delta loop wire blasted by continuing strong winds.  My 1W was achieving a 5dB stronger signal, Watt for Watt, than my compatriot (G4UGD, -23dB at 5W, vs my -25dB at 1W).

Extending the spotting period to 12 hours yielded the exact-same result.

AI6VN reception spots ~17-18UT period.

Very usefully, the outstandingly excellent Proppy HF propagation tool now permits user-defined signal bandwidth and detection levels to be entered, yielding realistic results for WSPR transmissions, at least for very to moderately simple antennas:

Basic circuit reliability for a Wales-KH6 path for 1W WSPR, November 2020.  Courtesy Proppy.

 

 

Starting in amateur radio

If you've hit this blog by wondering and searching about amateur radio, then welcome!  

It's a great time to start getting yourself organised to pass a fairly straightforward test, or series of tests, to obtain your licence!

Why?

Because the Sun has, over the past month, swung from a deep sleep state into a waking state.  The number of sunspots has risen in October to around 15, up dramatically from the previous month's number of 1.  For the next few years, the Sun will rise to full activity before, somewhere in the early 2030s, going to sleep for a while once more.

In tandem with this is a background reduction in the number of days when there are no sunspots:

Number of days without sunspots, by year.  2020 clearly shows solar cycle 25 has begun in earnest.

 

More sunspots means better conditions for propagating your radio signals from here to there, especially at the higher HF bands (see PE4BAS' recent post about long-distance contacts at 10m), where the smaller wavelength means antennas are smaller and easier to erect.

This solar cycle also brings to the bands more digital (computer-based) signal modes than ever before.  This opens up opportunities to capitalise on very brief and borderline conditions where signals are able to cross large distances.  

So effective are these computer-based modes that no longer is there a strict requirement to put up a huge antenna or use enormous amounts of power; simple wires and a few Watts are all that are needed to enjoy global communications, provided you also exercise some effort and patience - this is not a 'switch-on-and-instantly-succeed' hobby.

A great educational hobby where computers and radios mix.  We really do need more young people, females, and those from minority backgrounds to come into the hobby, and all are very welcome!

 

Also, if you don't really have the time or inclination to have a 30-minute chat, maybe with an older person on the other end - which most young people, in particular, find very offputting - then there is absolutely no need to do so.  Digital modes let you make a contact that can be simply something like scoring a simple hit for a logbook, or something more meaningful, such as a keyboard-to-keyboard, internet-like exchange in real time.

If you want to pick up a magazine, Practical Wireless is a great publication that isn't stuffy and exclusive in its approach, but practical and friendly.  Even though it, like all other magazines carries adverts for sometimes very expensive equipment, you can get an effective new radio for about £650, or significantly less if you carefully opt for a used item.  All you then need is a power supply unit and some cheap wire to get started.  

And for even less money, you can talk to someone far away via a space satellite!  At the moment, radios of low power that will allow you to make some contacts this way are selling for just £19.99.

So, if you are thinking of joing in the fascinating, educational hobby that is amateur radio, search online and get in touch with your local club and ask about any training they provide.  This is one advantage of the Covid era - more clubs are now offering live or recorded lessons online for all, usually at little or, like this very popular site, no cost!

My view on why radio is great?  Your mind, if not your body, rides along with your radio waves to far away places you may never even have heard of, and learn about the world.   And there is a lot of world to learn about...