Let's try to beat the Yagi!

Yes folks, I may have many faults.  But lack of dedication to the cause is not one of them!

Though it's difficult to make the time at the moment, I did manage a brief visit to a beach with a clear sea horizon from NNE to SSE this evening, to see how well a 1/4 wave vertical, using WSPR, would compare with my 12m LFA aimed at Scandinavia.  I was glad to find some tourists again take an interest in what I was doing; this is a very good way to promote radio if you explain things in a lively, jovial manner.

Looking east, towards Scandinavia, from IO73

The sea is a fair way out but the tide was flooding.  The sand, as is typical on very shallow beaches like this, is permanently saturated with seawater when the tide is out; you can actually see the water break the surface to the right of my rig box and backpack. I know from lots of earlier work that this acts to reduce ground losses pretty much as well as if the water were at the antenna's base.  Modellers always get it wrong, in that they treat a beach as though it is perfectly dry land, a bit like rock or concrete, and then have a sharp dividing line between its poor characteristics and the sea's much better traits.  The reality is very different.

Location (IO73ui) of beach operations.  Lines indicate limits of clear view (north at top).

Relative position of antennas. Yagi just to the south of the Parys Mountain label, vertical on beach at Lligwy Beach label.  Image: Google Earth.

So, how did it go?  Well, Es is of course the dominant mode at the moment.  Closer stations in Denmark were coming in at a tpyical 5dB better to the Yagi, compared to my vertical.  Better by about 4dB than when I took the vertical to the copper mine hill.

Beaming Scandinavia - at considerable expense, effort and visual impact.

But there were three stations at greater distances that produced remarkable results.  Remember, there aren't many stations active on 12m WSPR, and beaming a specific direction means there are even fewer.  Robust results would need a long period of study, but these are pretty reliable, all the same.

SM2LTA came in at -22dB to my 3-ele Yagi.  In the vertical on the beach - wait for it...-5dB!  A 17dB advantage to the vertical!

OH6BG produced an 8dB better signal in the vertical than the Yagi.

LA3JJ heard my 1W at 6dB stronger than the Yagi. 

There's no doubt that, at and beyond 1000km, the enhancement from the beach location can be very strong.  The explanation is definitely ultra-low arrival and departure angles that are inaccessible to the Yagi.

We can see this in action with standard models built into MMANA-GAL. First, the Yagi on my estimated ground conditions, 10m above that ground (most of us can't manage much higher than this, certainly in the UK):

If you plug-in perfect ground conditions (below), there is no practical difference - the peak gain (which is at 30 degrees elevation) - is only 0.3dB greater.  In both cases, you can see that by the time we get to 5 degrees above the horizon, the gain over an isotropic radiator has fallen to the -10dB ring, which is therefore a realised gain of just 2dBi.  Anything that renders the ground ahead of the antenna less than perfectly flat will reduce the low angle gain even further.

But don't get hung-up (great tune!) on the gain at 5 degrees elevation, because this isn't very low at all!  1 degree is a good place to start talking about 'low' angles, by which time the Yagi's pattern line is intersecting, approximately, the -25dB arc, or about minus 12dBi gain overall.

It's easy to see how this all plays out in favour of the vertical, when we look at its (vertically polarised) pattern over seawater:

The gain peaks at ultra-low angles, giving plus 6.65dBi all the way down to the horizon line.  If we add 6.65dB to the negative gain of the Yagi at these elevations, then we get up to around 18dB - which is the gain seen in reality with the case of SM2LTA. Possibly a simplistic analysis, but the general picture is not far from the truth.

Well, I'm glad I did that experiment.  Not that everyone will accept the results.  In recent correspondence, I see such idiotic nonsense as "yes, but not everyone lives near the sea", which is like saying you shouldn't use a car if you happen to have one, because not everyone does.  If I live near the sea, I can - and will - take advantage of it.  I hope others reading this will, too, because you get world-class performance from little more than junk wire!

OFCOM is not your friend.

The fallout from the new licence conditions concerning RF safety compliance continues.

Over past days, I've been reviewing the consultation documents that ran some time ago now. 

I was a surprised to find that the RSGB had, eventually, found it "impossible to support" the proposed new rules as they were presented.  This seems to have been a volte-face, because when news of all this first surfaced, the relevant RSGB representative gave a very firm impression of being fully behind it all.  The reason for this U-turn would appear to have been the outbreak of widespread dissent amongst the membership.  

Not that it mattered, because OFCOM went ahead anyway.

More worrying to me was the manner in which OFCOM started to engage in the kind of explicit disdain for public input and process that now characterises much of the current right-wing UK government machine.  

Entirely legitimately, and as is very common practice, the RSGB had issued standard response forms that members could either simply put their names to and send to OFCOM, or else use as a starting point for their own, perhaps more individual submission.  It was, after all, a complex area where the RSGB could and should have been expected to help members understand the background and make their views known.

OFCOM, to my mind very distastefully and in a manner unbecoming of a body that should have some sort of respect for the public and spectrum users, decided to go to town on all this 'copy and paste' protesting.  They "note" how many objections were submitted using the RSGB form, suggesting that this made them in some way illegitimate.

Now, if someone handed you a form about overthrowing the government in the street, and asked you to put your name on it, you would expect that, in very short order, to be used as evidence against you by the authorities.  They wouldn't turn around and say "oh, your name's only appeared on a standard form, so it doesn't matter - you are free to go".  

No, OFCOM, the world is not like that.  If someone uses a template or other standard form to make their voice heard, then it is the fact that they are making a representation, and not precisely how, that is important.

This story is not over.  I still haven't seen a single piece of peer-reviewed work that indicates there actually is a demonstrated risk to health from the frequencies and powers typically used by amateur operators.  And I have tried everything in the book - including statutory requests to OFCOM, Public Health England and a plea for information from ICNIRP itself.  

I'm still prodding these people to explain on what basis - other than what they accept was now concern about social media-promoted public hysteria about 5G - all this was dumped on the amateur radio community, who, again by OFCOM's own admission, have never been shown to breach any EMF safety limits.

Moreover, I still can't find a reasoned justification from ICNIRP as to why they deem 'HF' to mean 100kHz to 3GHz, whilst everybody else, including a 2012 Public Health Agency report, defines it as being 3MHz - 30MHz.

And, sadly, the more you look, the more it is confirmed that supposedly informed organiations like OFCOM and WHO have been simply jumping to the tune of the ignorant, hysterical public, who share their idiotic ideas online as though that makes them legitimate.  Almost all WHO information about EMF safety falls under 'mobile phones'.  We are not mobile phone operators.

We have been thrown under the bus, and OFCOM should not be allowed to get away with any more of this nonsense.  As the RSGB itself writes, in failing to identify any known breaches of ICNIRP guidelines (noting they are guidelines, not law), OFCOM appears to have broken the law in introducing these controls.  That kind of failure to adhere to legal requirements is, again, very much in the spirit and manner of the Boris Johnson government.

 

12m from the seaside.

Weather improved to warm sunshine last evening, so off we went to see the local porpoise family, and play some WSPR radio!

12m, out to sea. Looking NE.

This was to see if I could narrow the gap between my 3-ele LFA Yagi and a 1/4 wave vertical, by moving down from the hill and ~2km directly onto the coast.

It's not easy doing WSPR at 12m.  There are very few stations active, and when using a Yagi in a specific direction, this limits things even more.  

12m spots with the vertical at the coast.

12m spots with my Yagi.  Note: it had been active for ~one hour before I began with the vertical.

The location on the coast is only metres from the water, but is rocky.  Accordingly, losses due to the ground must be much higher than were I on damp sand.  

For now, we live with what we have.  I did in fact see a reduction in the advantage of the Yagi, from 9dB on the hill (accepting a very limited amount of data), to 5.5dB at the rocky coast.  

The range spanned 12dB (OZ7IT received by me) in favour of the Yagi, to 0dB (SM7PNV hearing me).  Yagi and vertical, in the direction of interest, had similar coverage in terms of stations heard or hearing, again noting the Yagi at home had been active for an hour or so before I set out with the vertical.

The SM7PNV spot highlights the crucial role of arrival angles; the zero difference to Sweden almost certainly indicates a very low angle not available to the Yagi, due to it being on land, and in a direction where there is low ground clutter.

I do expect that, when I take the vertical onto wet sand, or at the water's edge, I will see a further improvement in the vertical's performance; my informed guess is by about 3dB, possibly a little more. 

[UPDATE - there are some very interesting results to come from a beach outing the following day]

And do remember that the outcome for the vertical would almost certainly be much stronger if my Yagi was inland and not, itself, on top of a hill with a direct view of the sea!

A crucial aspect, though, with 12m is that Es leads to very large variations in signal level (I saw 11dB) over short periods from any given station, and so it is absolutely essential to use simultaneous spots for comparisons.  Averaging non-simultaneous spots, even over the same operational time span, may lead to incorrect conclusions.

 

9dB

Last night, far too late in the day, and with some rain showers around, I decided to compare a vertical antenna up on the copper mine 'mini-bog' site against my 3-element LFA Yagi at home, just a few hundred metres away.

Well, I only managed one simultaneous spot from both, such is the paucity of active WSPR stations at 12m. But three spots were obtained within a few minutes of one another, so that gives a slightly better picture.

Beaming North America - against my simple vertical!

 

The single simultaneous spot was to KD2OM.  I have to say I was very surprised to find the difference in favour of the Yagi was only 9dB.  The three spots within much the same period, but not simultaneous, gave 10dB in favour of the Yagi.

Of course, this is a big difference; you get ten times more effective signal from the Yagi than the vertical.  

That said, it will be interesting to now take the vertical to the water's edge and see whether it can erode that advantage.  We'll see if I can make some time this evening.

Whilst the Yagi is a superb performer, it is a relatively complex beast to put up in the air, rotate, maintain and - a big issue here - protect from frequent hurricane-force winds in winter.  All that sometimes causes worry.  To be perfectly honest, whilst putting up a beam is very nice and give a sense of achievement, the hassle of it all for an additional 9dB over a simple vertical is not a favourable equation, at least for me.

In the meantime, for those starting out, or simply curious, here's a sweep of the whole 12m band when using my 1/4 wave vertical with 2 elevated radials at about 1.5m feedpoint height above ground, radials sloping: a flat SWR, for this very narrow band, of just over 1.2:1

Although it's by no means necessary, you can bring the match closer to 1:1 by using a small coil connected between the radiating element and the radial connection, as shown in the image below (it's the orange coil at lower right, used in this case for another antenna experiment):

6m to Alaska

No.  First of all, I didn't know about the 6m opening yesterday to Alaska, nicely reported by EI7GL.

It's certainly an unusual opening.  But it struck me that, though it's a trans-polar path, it's not such a long distance.  We can wrongly think Alaska is spectacularly far away because of the way a sphere is depicted on a flat map.  EI7GL's leading map of the event has dramatic-looking lines that seem to go on forever.  Not his fault, but a product of mapping techniques.

If we look at that flat map, we tend to go 'oooh - so far to Alaska!':

But when we look down on the pole and use a spherical projection, suddenly things look far less impressive.  

The dotted line to the contiguous US is a typical Es path that is seen on many days during the summer season (it's open today, in fact).  It's about 6300km.

The line to Alaska you can already see just by eye is of a very similar length - it's only about 500km further, actually:

Yes, polar fading and so on does make this a path less likely to be successfully worked, and there are of course not so many operators in Alaska anyway.  But we shouldn't be deceived by flat representations of spherical surfaces.

Not that I would complain, had I actually made a QSO with Alaska yesterday!

Let's try 15m...

Another fairly nice evening brought me out with a 15m 1/4 wave vertical onto the hill yesterday.

21MHz from the hill.

I went a little higher up the hill, but to a place that is quite dry and rocky, even though the mineralisation of the ground is very high.  I know from 17m work that it doesn't produce results as good as the wetter ground a few metres lower down, even though it has a much more open aspect in all directions.

All the same, the site produced the goods: KFS heard my 1W at -24dB, but not my vertical delta for the band at all.  The only other UK station he heard came in 8dB weaker than me on a Watt-for-Watt basis; plot is for a full 24 hours' of reception by KFS, which just underscores how few European stations are making it across at the moment:

KFS receptions at 21MHz 05-06 July 2021. 

Reports for the vertical delta loop at home.

Reports for the vertical on the hillside.

Both antennas got 1W across to N6GN/K at 7125km, but with a modest enhancement to the vertical on the hill of 4dB.  But at K9AN, the difference was 8dB - more typical of what we see at 17 and 20m.

Whilst these enhancements might not appear to be enormous, they are certainly significant: a 4dB enhancement turns 5W from a QRP rig into nearly 13W, whilst an 8dB improvement takes us to 20W from the same input. 

It's definitely cycle 25...

No doubt about it.  Good radio days are here again!

Today's Sun.  Courtesy of NASA/SDO and the AIA, EVE, and HMI science teams