A few more observations on 144MHz ionoscatter

This is further to my last posting on this subject which  you can find here or here:-

 https://gm4fvm.blogspot.com/2023/06/ionoscatter-opening-on-144mhz.html

I got this screen grab of a similar opening a few days later 

144MHz Ionoscatter traces received at GM4FVM on 29 June 2023

The appearance of these traces certainly made me think that this was another Ionoscatter opening. I heard several stations and I worked SM5EPO (JP80) and SM5CUI (JO89). I have worked SM5EPO a few times - 41 contacts in the past decade on 50MHz ranging from PSK, JT65, JT6M, MSK144, and SSB (!) to FT8 but this is only the second time I have worked him on 144MHz and the first on Ionoscatter. 

A few points struck me:-

1) for the third time in a row the opening was mainly towards Sweden and Finland

2) there was no Es or Iono opening at the time on 70MHz, and nothing significant on 50MHz. Can it be true that 144MHz Ionoscatter is a different from that on the lower bands? Or, more likely, perhaps the angles are just different.

3) the opening lasted for over an hour starting with my first decode at 14:02 and ending at 15:04, but undecoded traces continued until after 15:30. Stations further south seemed to do better at the start but I did not come into the shack until 14:30 so perhaps I was not beaming correctly at first.

All of this makes me think that this was definitely Ionoscatter, and most others thought the same.

I have been wondering how I have missed this propagation mode for so long (erm, 48 years ...). Maybe because I did not have enough gain in my antennas, so perhaps it was worth spending the money recently for the mild upgrade.

73 Jim

GM4FVM

My current antenna situation

I just wrote a long posting explaining everything about why I have two masts, why the 6m antenna cannot go on one of them and why the 23cm should go on the other. It explained why I need to have at least one antenna covering two bands (even though I dislike that whole idea) or none of it works, and why I do not like sleeve fed single coax dual band antennas. Boring. I deleted it.

So you will just have to take it as read that I need to deploy them the way I do. Yes, I would love one taller free-standing mast with a stack of antennas on top, but it is never going to happen, so I have to do this.

This is where I am now. It is very similar to the last settled situation a while back. It might be settled now after a whirlwind of changes which went off the rails when I could not complete the programme, I was in the middle of swapping things around when my knee went and it has taken about 18 months to get the new knee fitted and for me to be able to work with them again now.

In the past I had the Dual 2m/70cm yagi with two feeders on my main "CUG" mast. The boom length of this antenna was 3m and I did very well with it over a period of five years. On 70cm, as with all designs of this type of antenna, the whole boom is not utilised and my single band SHF/Wimo 70cm yagi with 3m boom would have given better performance.

After a lot of head scratching, and some chin stroking, I decided that my 3m boom limit was getting in the way of results on those bands. However, stepping up to about 4m boom length put me into territory where no suitable commercial antenna was available. Most manufacturers stepped straight from 3m to 6m. I can hardly blame them as going to around 4m was only going to produce 1dB or so of gain, but that was not the point. I could free the 70cm antenna to be the full 3m boom if I switched to separate antennas, and that was what I did at first. I changed over to a I0JXX 8 element 2m single band yagi with a 4.2m boom, and put the SHF 3m boom back up for 70cm.

I have to say that the I0JXX is a beautiful antenna. Not only does it look wonderful, it performed brilliantly. It is light and strong, so what more could I want? The 70cm SHF also did very well, but therein lay the problem.

The only place to mount the single band 70cm antenna was on the Tennamast and that caused RFI problems. Also, and for the same reason, it broke (the UK regulator for amateur radio) Ofcom's rules setting limits for field strength outside the boundaries of my QTH. The Tennamast was too close to the boundary for the higher RF levels once I got my 70cm linear working again (that might be a later post). The solution would be to move 70cm back to where it was, on the same boom as 2m, as the CUG mast is far enough away from the boundary to comply. BUT, I had already moved it away from there as the dual band antenna lacked gain. I cannot put three antennas on that mast, and the 6m one will not fit anywhere else.

There did not seem to be a sensible answer so I took my standard approach and left it on the side while I worried about something else. When I eventually returned to thinking about this I decided to check out all the figures. It was then that I discovered that Dual now make an antenna with the same boom length as the I0JXX, with similar gain figures for 2m, but which also covers 70cm. Although the 70cm side is shorter than the 2m one, it is as long at the SHF yagi and the claimed gain figures are almost the same. Result!

Here is a photo under threatening skies.

The new Dual 2m/70cm yagi above the 6m PowAbeam at GM4FVM

2m and 70cm back on the same boom with broadly similar performance, and complying with the Ofcom rules? Just what I needed, but at a price. I had to buy a new Dual "PA144-432-25-4.5-2CAP" which has 9 elements on 2m and 16 on 70cm. This set me back about £250 but it should resolve RFI issues created by the SHF yagi being mounted too close to the site boundary.

Compared to the previous settled arrangement with the earlier Dual antenna, Goran claims +1.3dB on 2m and +1.8dB on 70cm. I am sure that this will not quite make up the difference to the single band antennas, but it means I can operate at full power which is +3dB. With the single band set-up I could not run my full power on 70cm. That did not matter until the linear came back. I might want to do some more moon bounce now.

To complete my antenna array, I am currently using my two 5 element PowAbeams for 4m and 6m. Once again this gives maximum performance for those two bands. If I need to in the future I could still revert to the single Dual 4m/6m antenna, but there would be some losses involved in that and no benefit which I can see at the moment. Later I might think of a reason for doing it (13cm dish Jim? That Mini-beam in the garage?).

The 4m and 23cm antennas are on the Tennamast. In that position and at lower power levels they easily comply with the Ofcom rules.

So that is it. Settled.

Until I change it again.

73 Jim

GM4FVM

Ionoscatter opening on 144MHz?

I am not very familiar with ionoscatter propagation. My knowledge has been limited to 

a) it is a forward scatter mode from the D layer

b) it peaks with D layer ionisation, so high summer at mid-day is a good time

c) it does not depend on atmospheric pressure like tropo

d) distances achievable are around 900 to 2000km

e) best frequencies are 30 to 60MHz, though up to 100MHz is sometimes quoted

f) it needs a lot of effective radiated power to work

The interplay between (e) and (f) tends to rule it out for me. At 50MHz I have 200W at the antenna, and on 70MHz it is 50-100W. On the other hand, at 144MHz I can put 200W to the antenna which has a lot more gain than is available on the lower bands. My ERP on 2m is twice what I have on 6m, even with the same power at the antenna.

So the only band I put out a reasonable ERP is above the ideal frequency for working Ionoscatter. I have read about it but I did not think it was for me. So, basically, I have ignored Ionoscatter so far.

As you may gather from this post, this period of overlooking Ionoscatter is now over. Yesterday was 20 June, almost at the Summer Solstice when the day length was 17 hours and 35 minutes here. Not a bad date for Ionoscatter. Mid Summer, mid day, a handy time to be looking for this.

There is an interesting article here  

https://www.qsl.net/oz1rh/ionoscatter/ionoscatter_lecture_2002.htm#_Toc10594132

The first sign I had that something odd was happening was hearing DK1FG working a local station. Now Gerhard is an EME operator with an antenna array with 10dB more gain than mine.  Also he has an linear amplifier with about 6 or 7 dB more than mine so his ERP will be tens of kilowatts more than mine, and probably a lot more. With the benefits of his much taller mast he will have several more dB over me there too, plus he has a superb site. With the advantage of antenna elevation he can also set his antennas to the optimum angle for ionoscatter. Despite all of this, I normally cannot hear him because under normal conditions no path exists. Hearing him yesterday was something of a surprise, working him was a greater surprise.

These were not "normal conditions". The distance between DK1FG and GM4FVM is 1128km, an ideal distance for ionoscatter. To achieve a contact like this we are exploiting one of ionoscatter's key characteristics. Whilst there is a ideal frequency range of 30 to 100MHz, this is not a strict limit. In fact as you exceed those values the losses rise but the propagation continues to work with more path loss until you reach the noise level. So by using an EME capable station at one end of the QSO it becomes possible to generate the sort of power budget which would make ionoscatter possible at 144MHz. Much lower ERP should work at 70 or 50MHz.

DK1FG's mast and antennas (DK1FG's QRZ.com site)

I do not have that sort of station but the path loss arithmetic suggests that a more modest station at one end of the QSO should be able to make ionoscatter work at 2m. From my point of view I decided to treat ionoscatter like moonbounce - I could not work a station like mine at 1000km range, but I might be able to work a superstation.

Actually using ionoscatter on 144MHz proved a bit tricky. Stations were on great circle bearings (unlike meteor scatter or aurora) but signals were patchy with what looked like steep QSB. It took a while to get a complete QSO. In line with the idea that around mid day would be best, I worked DK1FG at 11:55 and then worked four stations up to 14:22. I also failed to complete with one station and worked another one which may have been tropo.

144MHz contacts at GM4FVM on 20 June 2023

I have put 100km circles on this map to show what happened next. The following QSO was with F5RZC. Jean-Francois also runs a powerful station but he is "only" 642km away and I can work him under slightly raised tropo conditions. I am pretty sure that this was a tropo contact, and although not very strong, it did not show the peaky QSB shown by the other contacts.

After that I worked SM5DIC (JO89 1197km), OH6KTL (KP02 1506), SM1HOW (JO97 1270) and SM0DJW (JO88 1240). I failed to complete with OH2FNR (KP20 1641). These are all good VHF stations with better antennas, receive pre-amps and power levels than I have.

So why am I rambling on about how much better stations these are? Because that is what is needed for ionoscatter. It would not be required for a tropo contact during a tropo lift at these distances. All the signs are there for ionoscatter, and this is reinforced by the operators sending postings to the cluster indicating that this was ionoscatter. 

I suspect that the contact with F5RZC was tropo. There was no other tropo around and it did stand out as unusual. However, it appears to be too close for ionoscatter. The others look more certain.

Could I do this again? Can I use it on 6m and 4m where is might be more effective outside the mid-Summer mid-day window?

P.S. During similar conditions today I caught this screen grab which shows the distinctive patterns on the waterfall. Tropo would have shown long slow QSB and strong signals, this shows patchy weak signals.

Set against this, I seem to have forgotten several days of nice tropo since the last posting. The high pressure collapsed, the tropo went away and that is why I noticed the ionoscatter.

73 Jim

GM4FVM

Greece on 2m, and a VHF lift.

I have been away for ten days or so. We went to the Netherlands. There should be a photo at this point of me sitting in a Dutch garden playing radio with my dongle and laptop computer. Sadly it turned out that we did not take that photograph.

So this is the only suitable photo there is, which is of me soaking up the culture in the Netherlands.

GM4FVM at De Rosier in Vught, Netherlands (photo Mrs FVM)

Well, it is in fact Belgian culture I am soaking up, but close enough.

Yes I did listen on my dongles, but obviously the performance was limited by using portable antennas. Anyway, it passed the time in what was not meant to be a radio holiday.

Before I left GM-land a reasonable tropo opening arrived, and this came alongside the annual Sporadic E increase.

6 metre band

50MHz contacts at GM4FVM 29 May to 6 June 2023

Although there was not a lot of very distant DX on 6m, I did work an all-time new DXCC in the shape of Lebanon. OD5VB was also the best DX at 3770km.

As usual, click on the images if you need more resolution. 

4 metre band

70MHz contacts at GM4FVM 29 May to 6 June 2023

Meanwhile, on 4m there were some nice openings which brought the 2023 DXCC list up to 22 countries. There was one new entry on the all-time DXCC list, Ceuta and Melilla (at last). I finally managed to work EA9IB on 50W after several years of trying to reach that territory on 70MHz.

2 metre band

144MHz contacts at GM4FVM 29 May to 6 June 2023

High pressure over the North Sea for most of this period helped a lot on 2m, but it was Sporadic E which brought the best results. My contact with Tom, SV8PEX, took two years to achieve. Back in July 2021, here, I posted this ...

"Later Thomas emailed me. He is as keen to work me as I am to work him. He confirmed what I had thought, that there was a large tropo duct in the Adriatic Sea, and that must have connected to the Es event. He said that he was hearing me for a long time, but he could not get through the pileup (!!!).

Maybe another duct, at either end, may make this possible eventually. My best 2m Es DX is still 2333km so it is not totally inconceivable. However, earlier in July I had emailed G0JCC with my view that working SV from here was "not practical". Clearly, once again, I don't know what I am talking about. Or maybe all those factors have changed my mind.

Still, SV8PEX heard me, and I heard him. That is good, but not a QSO. Next time, maybe."

Now I have made the QSO. Two QSOs actually.

I have been in touch with Tom again. In fact I worked him twice, with about 40 minutes between the contacts. Initially I was unsure if the first QSO had been completed, so when I saw him calling again with no reply I risked calling him a second time. He confirmed later that both QSOs were complete.

Once again, I suspect that this was tropo linking into Sporadic E. Double hop Es on 2m is pretty rare and the distance to SV8PEX is 2408km is too far for single hop. Whilst I have worked 3260km on tropo that was fairly unusual too. That contact with EA8 was mostly over a sea path, whereas here to Greece involves crossing Europe and the Alps along the way. Not being mostly a sea path and with high mountains in the way makes me doubt that this could be tropo all the way.

It seems to me that as the ends of the contact were over the sea (the North Sea at one end and the Adriatic Sea at the other) then probably tropo over one or both extended the Es far enough to make the contact. I did work some other stations around this time, S5 and 9A, but nothing further than SV8PEX. New DXCCs do not appear on 2m so often any more, so that was much appreciated.

Incidentally S51AT appears on my map in the wrong place. I must have entered the wrong locator. I have now corrected that in my log. I must be more careful ...  

70 centimetre band

432MHz contacts at GM4FVM 29 May to 6 June 2023

Activity on 70cm was pretty low by comparison. However, I always enjoy UHF DX, and 31 QSOs in 8 countries is certainly not to be sniffed at.

 23 centimetre band

On 23cm I worked OV3T and OZ2ND. Not worth a map, maybe, but I still reckon that a couple of contacts over 650km at 1295MHz is a pretty good outcome.

====================================

The weather in Netherlands was pretty good and the high pressure has continued until my return, so there may be some more high VHF contacts to list shortly. 

I am sitting here listening to South Norway Coastguards, and I just worked LA on 1296MHz.

"Nae bad" as they say round here. "Pas mal", as I might say in some other setting.

73 

Jim GM4FVM

My dalliance with FT4

I have had two QSOs on the FT4 mode.

The WSJT-X guide (see sidebar for WSJT-X site) says :-

FT4 is designed for contesting, particularly on the HF bands and 6 meters. Compared with FT8 it is 3.5 dB less sensitive and requires 1.6 times the bandwidth, but it offers the potential for twice the QSO rate.

As I tend to operate at low signal levels on VHF and I never enter contests, this seems to suggest that FT4 is not a mode for me. I have been following the developments but I did not get involved until recently.

However, I see that FT4 is gaining a following on 70cm for the simple reason that the higher QSO rate means that contacts can be completed during short openings in propagation.

On 432MHz modes of propagation such as aircraft scatter often lead to very brief openings but they can produce moderately strong signals. Thus it might make sense to sacrifice some sensitivity to complete a QSO in half the time which otherwise would fail. FT4 might produce a lower signal to noise report but lead to a completed contact.

My first use of FT4 was with Jeremy M0XVF on 70cm at a distance of 133km. For me just a test of the mode on steady tropo. It is amazing to see a QSO completed in just over a minute, rather like a CW contest contact. The procedure is the same as FT8, just that the period is 7.5 seconds and the signals are wider.

My second, and so far final, QSO on FT4 came on 50MHz. Rather than 133km it was 11392km. I was trying to work LU3CQ on FT8 when he announced that he was moving to FT4. I went after him and he worked one station and then me and then was gone. He gave me a report of -18 which was a bit borderline but I was happy to work him for a new country and a new square on 50MHz.

All time FT4 contacts (both of them) at GM4FVM up to 27 May 2023

It took me a week to realise that 11392km is a new distance record for me on 50MHz.

All this just goes to prove that each data mode has its advantages. 

The biggest advantage is to be on the same frequency and the same mode as the station you want to work. This generally helps. It would not have stood me in good stead to have stuck with my previous mode and missed the contact entirely (AM users please note). So I did what I needed to do and switched to FT4.

Largely, different data rates produce a trade off between sensitivity and the period length. So WSPR in standard form has a very slow data rate and so it is very sensitive but it takes a minute to send very little data. In fact it has such a low rate of data that in that minute only beacon information can be sent. You cannot have a QSO on WSPR because the rate is so slow. You can slow WSPR even more - down to sensitivity allowing decodes at -45dB, but it takes 30 minutes to send and everything from the frequency to the propagation has to be very stable.

On HF many people are willing to trade off sensitivity for speed by using FT4. So good is propagation at HF that many operators do not realise that they are giving up 3.5dB in exchange for an early lunch. I cannot really see the point in this in most situations where FT8 would do the job rather better. Maybe this shows that I am a DX-er at heart. More sensitivity and decoding further into the noise is good for me. But at 70cm where propagation can be very brief I suppose that I can see the point of using FT4. 

Anyway, FT4 equals higher data rate, faster QSO, and less sensitivity than FT8. If you cannot hear them you cannot work them, so I prefer FT8 if I can.

As for working my first Argentine station on 6m, well, using FT4 was LU3CQ's idea. I just followed him. I made a deal with the Devil of FT4 and this time it worked. I know that I have to be on the mode that the other station is on or it is not going to turn out well (SSB users please note). 

I do not make the rules, I just follow along like a tender behind (a locomotive).

I need to think about using FT4 at UHF. If it proves to be the right mode then so be it. Maybe giving up some sensitivity is a price worth paying for more contacts. I suspect that Q65 would be better, but then Q65 is better is many situations yet few people use it. Or what about FT9F fast, which seems to be totally forgotten? 

Amateur radio is the art of the possible, and there is no point sticking to impractical modes if they do not meet a need (RTTY users please note). Popular modes like FT8 make lots of things possible, while little used modes might be better in some situations but are not much use if only you are using them.

This "I was only following orders" excuse for switching to FT4 and working Argentina on 6m is hardly good enough.

I need to look back in my excuse list for a better wheeze.

73 Jim

GM4FVM