Since AA7FV told me he was receiving the strongest spots he'd ever seen on WSPR at 14MHz, I've been taking more of an interest in what's going on.
Last night, the signal reached a new record, with two spots at -2dB SNR from 2W into a large rhombic antenna at AA7FV. My antenna is a vertical delta loop in quiet conditions.
The pattern of the spots, when plotted out, looks like this. Y scale is SNR in dB:
The pattern, which comes to an abrupt halt after the 00UT spot, clearly trends upwards from a fairly low SNR in my local early evening, peaking strongly in the period 22-00UT.
I've noticed this kind of thing many times before, and the timing appears to be related to the passing of magnetic midnight at roughly mid-Atlantic longitudes:
Situation at peak spot strength. Image NOAA.
The great circle path between AA7FV and myself is thus:
Great circle path. Image: Google.
The path, if it is the same as the great circle path (which may not be the case) from AA7FV goes straight into the magnetic midnight sector where it finds a quiet conditions aurora between Greenland and Iceland, although the signal enters the overall auroral oval much earlier, over the northern extremities of Quebec.
It is possible, perhaps even likely, that the AA7FV signal takes more of a tangential path to the aurora that may then skew its path towards the UK. This is very difficult to demonstrate, but has certainly ben noted in abundance in the scientific literature, where up to 100 degree deviations from the great circle path have been determined.
Superficially, this seems to suggest that some form of enhanced ionisation exists in this auroral zone that considerably boosts the signal strength over what it would be without it. This occurs repeatedly from night to night, so the link with the auroral oval seems strong, especially as the signal vanishes soon after my local midnight.
As always, any informed insights welcome under comments!
Propagation has been a bit rubbish over the past few days, and efforts with my special call GB0BYS have been tough going, despite managing contacts on all bands from 80-10m with one day left to go.
I had an interesting email yesterday from AA7FV, based about 15 miles north of Tucson, Arizona. The title was 'What antenna?'
Darrel, an UK ex-pat, told me of his surprise to receive a -3dB S/N report from my WSPR reception on 14MHz, using the GB0BYL call.
Darrel commented, speculating that I "must have an extraordinary antenna there to be able to
give me a -3 dB s/n report"
"I have rarely - in fact I think never - had such a good report
from Europe or the UK. Other WSPR reports I was receiving from
Europe or the UK at the time were typically 20 dB weaker than
that."
Darrel knows what he's talking about. He's a semi-retired professional astronomer with a Physics Ph.D. from Cambridge University. Even better than his academic qualifications is his rhombic antenna pointing at Europe. A rhombic like this has a typical gain in excess of 15dBi on its main, very narrow front and rear lobes.
Even with my standard vertical delta loop as the antenna for 14MHz, I've managed contacts - either TX or RX - when others are unable to, over a long period of time and I've blogged about them regularly. Others tend to think this is machoistic bravado, but I see it only as reporting what happens from a clear, elevated, highly mineralised site overlooking the sea. Magic and bravado aren't necessary. The environment and consequent antenna pattern (i.e. extremely low, even sub-horizontal radiation) is what makes it all happen.
To reinforce the great potential of my QTH, I happened to pick up the tiny 10mW from ZL1RS' BB05 balloon, and making its way eastwards across the Pacific, lying close to Easter Island at the time.
Now tell me the QTH isn't a good radio site!
The critical thing is that, at the time of consulting the WSPR database (evening of 27/04/2018), I was one of only two stations across Europe, Africa and Asia (one station from JA) that had heard from the balloon since its launch, 3 days earlier. Curiously, ZL1RS says that the transmitter is 50mW, whereas the WSPR reception reports issued by all stations claimed 10mW. Either way, it's a long way for a tiny signal, even from 30,000 feet and a full vertical dipole dangling underneath the balloon!
So, I think I am now content, faced with all this entirely non-biased, human-free WSPR assessment, that this QTH is very special for radio, and that it yields world-beating performance from simple (but always well-made and matched) wire antennas.
I hate to think how much time I've spent building antennas over the years. But one thing I don't have to worry about is having spent too much money on them.
A long time ago, I wrote about a simple multiband end-loaded vertical that has, by a very wide margin, become the most read article of any in this blog. I'm also glad to say that a number of people have contacted me to tell me how they built their own and found it very effective.
A 20-6m vertical for £50 or less!
Spending more time at my 'weekend' shack these days, I decided to finally deploy my all-aluminium version of the I-AM antenna in the field. This has been lying around under various stages of development for around two years, so it was nice to get it away from the garden and into practical use!
The main advantage to me at this site is the ability to reliably and quickly disassemble the antenna into smaller parts that can be stored when not in use, and the rapid deployment due to there being no radials or much by way of a support mast, etc.
The antenna in this version is also very physically strong, and can withstand the kinds of accidents and occasional encounter with cows and sheep that operating in the field inevitably brings!
To recap the basics:
The antenna is a vertical dipole, except it is made physically much shorter by cutting each 'leg' in half, and joining the other half on top of the first in a 'T' arrangement.
Aluminium (and many other materials) are often sold in 2.5m lengths, which makes them readily car-transportable. This is very useful, because the electrical length of each leg of a 20m dipole is almost exactly 5m.
Using simple 'wing' nuts that can be operated easily without tools, the horizontal end loads can be attached and detached from the vertical sections for easy transport/storage.
Insulation between the dipole legs can be achieved by several methods. The original version I built was simply timber end load supports with wires running along them, then some vertical wire strapped onto a fibreglass (insulating) fishing pole. For the current version, I used Delrin plastic inserts both for inter-leg insulation and as the physical support at ground level, which also needs to be insulated.
Feed point contacts in my case are metal straps secured to the poles with stainless steel hose ('Jubilee') clamps. A better arrangement that I will use shortly is a bolt through the pole, and a ring connector from there to the feedline.
The commercial version of the end-loaded vertical is the I-Pro Home, currently sold by Nevada at £259. There has recently been talk of Pro Antennas returning to sales in their own right, but their website is currently (21/4/18) reporting a '404'.
Easily split into two halves for storage/transport.
The cost of building your own I-AM antenna will only be roughly £50 in all-new materials, made up mostly of the aluminium tubes and Delrin rod. Other bits you will have lying around. Ebay is a good place to find all the materials if you choose your sellers carefully.
The I-Pro Home commercial antenna uses a 4:1 transformer at the feedpoint of the vertical. Whilst this works just fine, it is not the best arrangement. Firstly, it adds substantial weight to an already rather top-heavy antenna.
Secondly, for an antenna that must be matched with an ATU on most or all bands, it makes much more sense to use a direct feed with 300 Ohm twin wire running either to a balanced line ATU, or directly to your rig or unbalanced line ATU via a 4:1 balun on the floor or a wall near the transceiver, and a very short length of coax to finish the connection.
Full HF sweep of my I-AM antenna in an open field setting. From 20m up (which is the design intention), the SWR remains within easily matched limits.
The reason for this is that the antenna works at relatively high SWR, where losses are very much higher with coax - up to 20 times higher - than if twin wire is used. The higher SWR itself is not a problem and should not be viewed as such, because it is, of itself, a lossless phenomenon. Those reflected waves do ultimately get radiated.
End load attachment method. Wing nuts permit easy mounting/dismounting.
Last night I confirmed again that this antenna matches up on 20-6m, although the internal ATU was getting towards its limits at 6m. With an external ATU, you will probably manage a match on 30 and possibly 40m, but it probably won't be very good on the latter band.
One solution for feedline attachment. A bolt with a ring connector is a better one!
My first call last night was to A41NN in a pile-up on 14.200MHz. I was rather pleased with that! I look forward to using the I-AM as my main operating antenna from this /P site from now on. UPDATE:
I had a very quick chance to run WSPR on 20m using a very old and simple manual ATU to my WSPRlite recently. Free time for a longer run will come at some point.
I compare my antenna with a GI station running 1W as opposed to my 200mW, who is known to be a very good performer and a consistent reference station for me.
As you can see, whilst the data is very limited, and mindful of the more than 6dB greater output from the GI station, the WSPR results do clearly show this vertical end loaded dipole is performing very well indeed.
A brief period of WSPR propagation testing at 10MHz the other evening revealed an interesting spot of my signal that I don't think I've ever seen before.
Because I've worked on smaller research vessels, I was very interested to see my signal was heard by GM0HCQ/MM, a WSPR station on board the RV James Clark Ross.
WSPRing its homecoming.
A look on the AIS site confirmed my expecation that the ship was returning home to the UK after a summer in Antarctic. The latest port of departure was Port Stanley in the Falkland Islands.
Although the recent survey on amateur radio is necessarily non-scientific and heavily US-centric, it is certainly worth a read and very thought-provoking.
It seems the clash of the generations is playing out in the hobby quite strongly, with old operators blaming youngsters, and youn operators blaming old timers. I guess it was always thus, but it is disappointing and sad to see a 'blame game' play out.
In late April 1986, I was listening to MW commercial radio from
Germany at home. It was advising people in Germany to close their
windows and remain indoors for a couple of days. There had been some
kind of accident in Ukraine.
A day or so later, I was out fishing for trout at my local lake on a fairly warm but very wet day.
Later that day, I learned about the true scale of what had happened. It was, of course, the Chernobyl catastrophe.
Whilst
it's over 1000 miles away from Wales, the winds on that week conspired
to flow eastward. Together with very heavy rain, this weather pattern
caused a considerable amount of radioactive fallout from Chernobyl to be
deposited on North Wales, especially the high ground of Snowdonia.
This
was more than a technological catastrophe. Countless people died and
many more suffered terrible health effects - and continue to do so.
Controls on the movement and sale of sheep in the more seriously affected areas of North Wales were not removed until 2012 - 26 years after the disaster.
So
this was a big event of the time. I always remember it and the grey,
rainy day where I was being soaked with radioactive rain as I fished by
the lake.
This
year, I applied for GB0BYL as a SES call to commemorate the 32nd
anniversary of the catastrophe. As I wrote the QRZ.com page, I thought
it would be a good idea to link the callsign on QRZ.com to a charity
that helps the children of Chernobyl, who continue to suffer terrible
diseases linked to the radiation loading from the accident.
I
also came to think that amateur radio is always repeating its claim to
be very useful in disaster relief. It's very much an US-centric thing
that doesn't really find much application elsewhere. Many of think it's
an exaggeration, others a falsehood, that ham radio has any significant
role to play in such work.
But I also came to realise that supporting worthwhile causes through raising the profile of charities via amateur radio is something we can meaningfully do, even if the increase in support and donations might only be modest.
According to an ARRL article I saw on the internet yesterday, the number of licenced amateur radio operators in the UK has risen by 10% over the past 5 years. Similar claims have appeared at an earlier stage, and have not always been accepted as being entirely accurate.
If true, this is good news. But are we doing enough to attract new and younger members into this wonderful hobby?
UK Labour Party's current message. Also should apply to ham radio.
Looking at the RSGB's Facebook pages, there was a nice feature about its demonstration radio station at Bletchley Park, the former WW2 codebreaking site.
I don't dispute that the RSGB should show some of the best modern technology that makes ham radio ever-more interesting and exciting these days.
Once you see the expensive stuff inside, you may be more likely to walk in the opposite direction.
But should we be presenting amateur radio to the public solely as something you can enjoy only if you have the latest SDR transceiver and remote-control head? After all, there is an entire generation in the UK now unable to buy their own homes, facing long-term falling incomes and rising prices. They are not likely to have a spare £6000 to spend on non-essential things like a radio transceiver, even less so a place to operate from free of RFI that might remotely justify such a massive financial investment.
Some of the Bletchely Park station equipment is donated by commercial outlets. Whilst the demonstration benefits from this, it is undeniably, at least in part, a form of advertising that pushes certain - in this case very expensive - equipment on potential customers. The PR value when the stuff is presented can also be very valuable, especially when several articles celebrating the donation are free, when an equally-sized advert in a print magazine might cost the donating company a large amount of money.
My first rig was £270 off E-bay. You can now get a new, basic rig for not much more than that. An antenna can be made from any old wire, provided it's strong enough to withstand the weather. 12V DC power supplies can be obtained for just a few pounds. It might not look space-age, but it is, in essence, ham radio all the same. Few of us buy a new Mercedes when we first pass our driving test. We build up to better things, if we can. So it should be with radio.
I asked the RSGB, using its FB page, whether it had any plans to show people how easily and cheaply amateur radio can be set up, rather than promote the kind of radio that only the rich retired can take part in?
I was glad to see the RSGB responded, saying it was looking at ways to appeal to newcomers to radio. I hope it doesn't need to dwell on it too long, because some of the answers are pretty easy to identify. Not portraying ham radio a hobby only for the wealthy is one of them.
DX has picked up lately. I found 10MHz was abuzz with VK stations on FT8 this morning, reminding me of conditions past on 14MHz, when the Sun was more active.
Over on 14MHz, a few minutes later, I found and logged R0LER/MM, bobbing about in the Okhotsk Sea and sending a very strong JT65A signal to the UK.
Making contact with R0REL/MM this morning. Terminator correct for time of QSO. Image: DX Atlas, with permission.
Here is a brief recording of the signal from R0REL/MM the previous day, where you can just about hear the distortion in the signal that is much more indicative of a cross-auroral zone path than a long path signal. If you can't hear it, you can certainly see the spread-out signal on the waterfall:
Video frame grab of R0LER/MM signal spread, almost certainly a result of crossing the north auroral zone.
So the DX is there, so long as you can manage some operating at breakfast time!
A short while ago, I posted a link to news that Solar Cycle 25 was probably arriving very soon - as early as summer 2018. This was a follow-on to earlier news about the first signs of Cycle 25 spots being seen by the Royal Observatory of Belgium at the end of 2016.
Now, more solid evidence of Cycle 25 having started emerges, this time from the University of Berkeley. This builds on a close monitoring of new sunspots by Jan Alvestad.
The Sun today (16/04/2018). Image: NASA SDO.
As I write, the solar disk images are showing another spot group appearing on the limb, which is more clearly seen in this image at 94 Angstroms:
It seems that we really are now at the bottom of the cycle, and that - perhaps - by the end of 2018, we may, just may, see a turn towards better conditions on the HF bands.
Last night, I ran some 40m WSPR tests. Because I'm as interested to learn who I am hearing as much as who is hearing me (and, often, more so), I prefer running WSPR from my transceiver.
Of course, tying up an expensive transceiver for long periods running WSPR is a bit of a luxury. That's why the diminutive WSPRlite units have become so meteorically successful.
So successful, in fact that if we take transmit powers of 23dB as a likely indicator of WSPRlite use on the WSPRNet reporting site, then between 40 and 50% of all stations on 40m last night at any randomly-selected period were transmit-only, WSPRlite units.
Becoming dominant?
It's great to see so many people having an interest in WSPR, of course. But the whole system does depend on people listening. No listeners, no reports.
The worry is that WSPRlite has only been available for a couple of years, yet has reached a very high proportion of active stations already. In a few years' time, the skew might well work against the whole WSPR system.
Ideally, we need a cheap WSPR-dedicated, data-logging transceiver. There must be an opportunity for someone to produce something like this, with a mind to low power consumption and simplicity that permits it to be deployed in challenging and resource-limited environments.
I've had a bit of a minor 'flu these past days, so had a chance this afternoon to fire a few 'CQs' on 12m.
Whilst I'm the eternal optimist, it's been pretty dead on 12m the last few weeks, so I wasn't expecting much today.
But there has been some geomagnetic disturbance the past few days, too, so things were a bit better than expected.
Suprise, suprise, XT2AW was busy sending a strong signal out of Burkina Faso on FT8, with only a small number of people active alongside. Whilst I am not a huge fan of FT8 on the busy bands, it is very useful on the lesser-used ones, where it can be used to quickly assess if anyone is out there, listening.
So I merrily logged a second QSO with that station, which last appeared in my log in 2015, also on 12m, but in SSB.
Way back in the 1970s, during the heady years of the Cold War, there was an awful lot of anti-Russian propaganda about in 'the West'.
I am glad today that my children don't have to grow up reading the kind of bizarre and frankly absurd 'advice' once issued by our government on how to survive a nuclear attack. In short, this advice consisted of ripping some doors off their hinges and somehow fitting an entire family underneath as the house was obliterated around you! Then again, it's the awareness of nuclear weapons that has been lost in today's younger generation, not the risk of a war itself. Perhaps that is a bad thing.
Though I was born in a backward, rural part of Wales, I did have strong curiosity about the wider world. I was always thinking: 'I'm pretty sure that all this stuff the government tells us about 'the Commies' is a bit biased, and I'm sure the people of Russia have no more enthusiasm for a nuclear winter than we do here'.
In a very real sense, the propaganda against Russia was one of the main reasons I was driven to take an interest in 'DX' radio. This initially took the form of turning on my dad's old valve SW receiver sitting in a very cold, spiderweb-infested workshop - the kind of receiver with city names like 'Moscow' written on the dial - and tune in to what was being said.
Of course, all sides, of all colours, were sending propaganda out in an endless stream. The current obsession with social media-based 'fake news' seems not to realise or to have long forgotten the era when hardly anything you heard on the radio or TV could be considered very reliable.
It took me a long time - many years - to take my interest up in amateur radio and pass the exam. But when I did, I found myself being very happy to speak to real, everyday Russians. Then as now, of course, there was no animosity between us, because we all just want to get on with our lives in peace, enjoying radio, a beer and sharing experiences from afar.
It is often said - and is always true - that if politicians were like amateur radio operators, the kind of warmongering that the idiotic Trump and the gangster Putin are today throwing around would not come to pass.
So, whilst we have our various differences, none are so grave that we should risk escalation to war. Life is too short, and time on the radio shorter still, to waste time on threatening and killing one another.
And messages like this (not sent by any of the identified stations), received on 14MHz FT8 this morning, have no place - at all - in ham radio:
This week's work in progress is a return to several years ago, when I tried out a pair of phased, elevated verticals for 20m. These worked well, but saw little service as my tower was due to be installed where they stood.
With more room now, I've ordered a couple of new 7m fishing poles and 75Ohm coax to make the necessary 1/4 wave stubs, this time for the 17m band. You can either use the foregoing type of online calculator, or an antenna analyser. In the latter case, you just connect an open-circuited piece of coax of slightly longer than the computed length to the analyser port and cut until the minimum impedance (close to or equal to zero Ohms) occurs at the operating frequency.
The basic feeding format for two phased verticals is, of course, pretty simple. It goes like this, using 75 Ohm coax from the 'tee' to bring a proper match:
The devil, as always, is in the detail. The maximum gain of two phased verticals, which is about 4.6dB over a single vertical (effectively taking 80W typial peak SSB up to over 220W), is achieved when the spacing between each antenna is at 5/8 wavelength, remaining at 4.5dB at 3/4 wavelength. Gain falls away rapidly beyond 3/4 wave.
The pattern of phased verticals is markedly different from a single element, in that you achieve a bi-directional beam, 'broadside' to the line of the verticals, rather than along their line, roughly as shown in the polar plot below (imagine one antenna at 0 degrees, the other at 180 degrees):
Now, for 5/8 wave spacing, at 18.1MHz, the physical spacing needed between elements is about 10.4m.
But each stub has to take the velocity factor (in this case, 0.8) of the 75 Ohm coax into account, meaning each 1/4 wave leg is shorter: only 3.3m or so long. Twice that is 6.6m. This leaves us 10.4 minus 6.6 = 3.8m short (1.9m each side of the 'tee') for the correct spacing, and then only if the cable is dead-straight and doesn't have to reach an elevated feedpoint. This is not the case for elevated verticals, and certainly not for vertical dipoles, yet is almost always ignored in books and articles!
Cutting my 18MHz stubs using SARK-110 analyser into an open circuit piece of coax. Minimum impedance at ~18.1MHz indicates the correct length has been reached. Note that the cable impedance selected within the analyser makes no difference to this analysis.
For coax that lies on the ground and has to climb, for this band, around 1.5m up a supporting fishing pole to the feedpoints either side, the total coax length is significantly longer than the diagram above implies if, as is likely to be the case, you are using a single, and not odd multiple of 1/4 wave for the stubs.
The shortfall is made up using the necessary length of 50 Ohm coax to reach the antenna feedpoints.
If we take that 1.5m as a reasonable feedpoint height, we need 3.3m of 75 Ohm coax as calculated, and then 1.9m minimum of 50 Ohm coax without any climbing to reach the bottom of each pole, and 1.5m on top of that to reach the feedpoint. Total length comes out as 3.3 + 1.9 +1.5 = 6.7m per side.
Overall, better to cut your stubs, then set up the antenna system in the field and see how much 50 Ohm coax is needed before cutting it off a drum!
And about 75 Ohm coax. I bought some of this from a major UK ham outlet, simply because I didn't have any lying around and I wanted to see what they, as opposed to the usual TV/satellite cable purveyors sold.
Turns out the 'ultra low loss' ham-specific cable was the same thickness as RG-213, but had a very much stiffer, very plasticky coat that makes working and using it less easy than had I just bought the usual, more flexible TV type coax. At 18MHz, it is of very little consequence as to whether the coax is 'ultra low loss' or not. Even the technical specs admitted the difference between it and the cheaper, 'low loss' coax at 10MHz was only 0.6dB over 100m!
UPDATE:
Unlike some books, I like to both write about the theory, the building and the real-world testing of antennas.
So, if you are wondering if the above article actually yields a working antenna system, I have just spent four hours in the mud and rain setting it all up, and the answer is "yes!"
Firstly, the total coax length is just about OK, and does not necessitate any changes, but could preferably do with being about 0.5m longer (of the 50 Ohm coax) on each side of the 'tee'.
It took me a while to figure out why, initially, the SWR was well over 2:1. This was not helped by a couple of hefty cows and their calves taking an interest in proceedings, but who decided to keep their distance eventually! I tried moving the radials from along the beam to side on to it, but this made no difference. There was some minor interaction with a nearby wire fence, and moving the radials away a little stopped that.
10m apart, giving a nice 4.6dB gain towards the camera (and the reverse, towards the trees) at 18MHz.
The first test day was very wet, with not only saturated ground but water running over the surface. So the antennas could well have been appearing to be electrically longer than expected. This is common to most wire antennas. The excessive length could also easily be down to using PVC insulated wire.
Rather than cut the wire at this early stage, I just bent a guesstimated 5 inches (127mm) of wire on the vertical radiating elements and taped it up. That length also turns out to be about 3% shorter - what we would expect with insulated wire, as noted above. I left the radial length untouched, but did raise the feedpoint from 1m to to about 2m (using all sections but the top one of a 7m pole), and the ends of the radials to much the same height.
Returning to the analyser, I found this simple adjustment yielded the good match across the band I was looking for. I could also see that moving the radials to slope markedly downwards tended to give a slightly poorer match. This is not usually the case with single element verticals.
Below, you can see how the array's matching eventually worked out, after some equal pruning of the radials. I also found the system has considerable sensitivity to the position of the feedline from the transceiver itself to the coax 'tee'. Like all antennas, it's important to bring the feedline away in as symmetrical a manner as possible. The match quickly becomes poor if the coax runs so close to one of the antennas that it lies within the diameter of the radial field.
Unfortunately, and in addition to lots of QSB, 3B7A was active with an enormous split pile-up taking a very greedy 15kHz of a very narrow 17m band. But I did manage to work 4X4FR at 59+ to me from his dipole, 55 from my array, probably completely out of alignment with one another's 'beams'. I later managed UR4MSF at a good 59 each way. That's actually not bad going, and in accordance with the propagation model, given the SFI of 67 and consequently quite terrible band conditions at solar minimum on this band.
My SSB QSO's in agreement with the ITUPROP model.
I also heard a JA station calling CQ, but could not change the verticals around for the correct beam heading quickly enough. Nobody was coming back to him, so he vanished.
The gain/null of the phased verticals is very noticeable. I could hear a Florida station in the US at about 54 rise to about 56-7 as I moved one vertical from a N-S pattern to give a E-W beam pattern. I could also hear the audio rise very clearly from outside the shack. A US-UK path was not predicted in the model.
The following day, I worked VO1CAL and KF4ZZY at 57 and 54, respectively, when the band conditions were very terrible and everyone was using 500W-1kW. I was only using about 80W peak output.
The array is not very cumbersome to set up or set down, and simple clothes line ground screws are more than enough to fix the fishing poles in place (in the UK, Wilko currently sell good, wide ground screws for £6 each). It's something that can easily be carried in the car. It's certainly a good system, with a good degree of gain for very little outlay. If you use kevlar-coated wire rather than equipment wire, this makes for infinitely fewer wire tangles, and is much to be recommended for avoiding angry outbursts on setting up!
