Analysis of Paul Logan's Band 2 FMDX log for 2020: Pt 1 - Tropo

In this three part series of posts, I am going to look at the 2020 logs of a very active Band 2 DXer and what they might suggest about propagation on the 88 to 108 MHz FM band. The posts are broken up into three parts... 1) Tropospheric Propagation, 2) Sporadic-E & 3) Meteor Scatter.

First off, a big thank you to Paul Logan who very kindly shared his 2020 Band 2 logbook with me and answered numerous questions that I had. Outside of his usual 'local' FM radio stations which he can hear under flat conditions, he logged and identified roughly 5,500 long distance signals on Band 2 in the year 2020.

Profile of Paul Logan... Paul is a very active listener of Band 2 radio (88-108 MHz) signals and has been logging stations that he has heard for about 30 years. He lives in Lisnaskea in Co.Fermanagh in Ireland and his location is shown in the map below.

Paul's location is far from ideal for listening to distant VHF signals. He has some local hills to the east as well as the hills and mountains in Scotland, England and Wales as a further obstruction.  

Equipment... For the 2020 logs, Paul used an SDRPlay RSP1 & RSP1A.

In recent years, software defined receivers have transformed FMDX listening as signals can now be seen on a computer screen as well as being heard. This allows a user to visually check for any unusual signals and can then go investigate it. One of the most impressive features is the ability to record sections of the spectrum and a user can then go back later to listen for anything unusual.

For an antenna, Paul is using a Korner FM9 from Antennenland in Germany.

This antenna which is mounted 8 metres above ground level is highly regarded by many FMDXers in Europe.

2020 Tropo Log... During the year 2020, Paul heard and identified around 86 signals that were heard via tropospheric propagation. This mode of propagation occurs when signals are bent over the horizon by sharp changes between air layers with different temperatures and moisture content.

I have picked out 5 groups of signals of note which I have marked from A to E. Refer to the map below and then the horizon profile further down.

A - This group of signals from the north-west corner of Spain are in the region of 1200 to 1300 kms. The sea path from the south coast of Ireland to the north coast of Spain is very good for VHF propagation with marine ducting happening several times a year. These sea paths are usually the best for very long paths in excess of 500kms and sometimes the signals can be amazingly strong.

In the video below, Paul shows how he was able to hear a Spanish radio station on a small portable radio when the opening was at its strongest. With his main directional antenna, he was able to hear the Spanish signals for most of the day.

In the horizon plot below, you can see that the path to NW Spain at Paul's location is largely unobstructed with only a 1 degree elevation. This allows very low angle signals to arrive at his location.

B - This path to Brittany and Cornwall is similar in that the sea path helps and the hills on the horizon are quite low at about 1 degree elevation.

C - This interesting batch of signals came from Norfolk in the east of England, a distance of 600kms. These signals had a few obstacles to overcome including Paul's local hills as well as the Pennines running down the centre of England.

With the signals arriving at least 3.5 degrees above the horizon, the means of propagation may have been via an elevated duct in the region of 500m to 2000m above the earth's surface. While higher frequency VHF & UHF signals tend to propagate better inside of ducts, it went as low as 89.7 MHz in this example.

D - This cluster of signals from the Netherlands and Germany were interesting for a number of reasons. First off is the sheer distance... about 1000kms which is unusual for Band 2 tropo. I suspect that the sea path over the North Sea may have helped for a large part of the journey.

If you examine the horizon plot below, you'll notice that there is a gap in the hills due east (90 degrees) where the horizon has an elevation of about 2.5 degrees.

What's really interesting is that the paths from the four transmission sites fit exactly in the gap. The signal from the most northerly German transmitter is exactly at the left hand side of the gap. The signal from the most southerly Dutch transmitter is exactly at the right hand side of the gap. The four signals fit exactly like a glove which suggests that they are coming in just barely above 2.5 degrees above the horizon.

E - These signals from the Newcastle area were at a distance of about 370kms and again are coming in from an obstructed path. This one has the highest angle as it had to clear a local hill that was 4 degrees on the horizon.

Outside of the five examples shown above, most of the other signals were in the region of 150 to 300kms which is pretty typical for tropospheric propagation on Band 2.

What's also interesting are the signals that weren't heard. For example, there was no tropo from Scotland which Paul confirms is a very difficult direction for him. As can be seen from the horizon plot above, the local hill in that direction is 5 degrees and that has the effect of blocking tropo signals.

In conclusion... I hope this short analysis highlights the importance of having a low unobstructed horizon for hearing signals on Band 2 (88-108 MHz). 

Having obstructions under 1 degree is best, under 2 degrees is acceptable but beyond that, the signals and paths get rarer.

Any local hill that is at 5 degrees or above is a show stopper for VHF tropo propagation.

The examples above would also apply to say the VHF aircraft band (118-136 MHz), the 2-metre amateur band (144 MHz) and the VHF marine band (156 MHz). 

Normally the best advice is to have your antenna mounted as high as possible on the VHF bands so that the amount of obstruction on your horizon is reduced to a minimum. 

Band 2 is a bit of an paradox in that the higher you put your antenna, the 'local' signals get stronger which in turn can mask the DX signals. It's really a case of finding out what height works best for your location.

Links...

1) Paul Logan's Tropo log for 2020 on the FM List website.

2) Paul's YouTube Channel

3) Paul's radio website

4) Paul's AM/FM DX Twitter account

How to check your horizon for HF & VHF propagation

If you're interested in the upper HF bands or any of the VHF and UHF bands then your horizon is all important. On bands like 144 MHz and above, the vast majority of signals are coming in from the horizon and just above it.

On bands like 28 MHz, 50 MHz & 70 MHz, the signals may be coming in at a slightly higher angle with Sporadic-E but they are still very close to the horizon. Whether you're operating from home or thinking or going portable then knowing your horizon can help explain what's going on.

First off, the website for checking your horizon is https://www.heywhatsthat.com/

In this post, we'll look at how to use it and some tips on getting them most out of it. To help explain it, I am going to do a profile of Paul Logan's location in Lisnaskea in Co.Fermanagh, Ireland. Paul is an avid listener to the Band 2 FM band from 88 to 108 MHz and logs hundreds of radio stations from all over Europe every year.

Getting started...

After going to the HeyWhatsThat site, click on the 'New panorama', zoom in to find your own location on the map and then click on it. 

I have done this in the example above for Paul's location and them zoomed back out. On the left side of the screen, your latitude and longitude will be automatically filled in after you click on the map. You can also select the height above ground so I selected 8-metres which is the height of Paul's antenna.

Note that the site uses the general topography to calculate your horizon, it doesn't take buildings or trees into account.

Also make sure to select 'Metric' at the bottom of the screen to use proper measurements.

Then click 'Submit request'.

Using the results...

After a short while, a map is generated. I clicked on the 'Visibility cloak' to show the areas that are visible from Paul's location. The Red triangles are distant peaks and I clicked on 'Contours' to highlight the topography.

This is that the horizon looks like for Paul...

I have exaggerated the vertical scale and added some numbers to make it clearer.

There is a large hill with an elevation of about 5 degrees to the north-east of Paul's location (45 deg bearing) and this is clearly shown on the image above. This would have a major impact on all signals at 144 MHz and above. As Paul notes himself, he finds it very difficult to get distant stations on Band 2 in that direction. 

That hill would also impact on all long distance single hop Sporadic-E coming from that direction on all bands from 28 MHz to 144 MHz. Short skip arriving at a higher angles on say 28 MHz or 50 MHz would probably clear the hill.

Due east at 90 degrees, there is an interesting gap which might might allow some distant Band 2 tropo or Sporadic-E through.

From 100 to 140 is another impediment to low angle signals but it gets much better after 150 degrees or so. Paul has a very good take off at about 190 degrees towards the Canary Islands and even those distant line of sight peaks around 270 degrees are so low that there are unlikely to be much of a problem. As a result, his location will be wide open to say the USA on 28 MHz once the sunspot numbers increase.

Example 1: Poor tropo path to Scotland.

In this example, I have shown what the path is like to Scotland and how the hill is in the way. If you are trying this from your location, then just click on any location of interest and the site will show you the path and where it is on your horizon.

Example 2: Good tropo  path to Spain

As can be seen from the horizon profile, Paul has a good path to the south and this can allow him to gain access to the marine duct that sometimes occurs between Ireland and Spain. The distance shown is about 1200kms which is really good for Band 2 tropo.

Example 3: Sporadic-E footprints...

Using the 'Up in the air' button, I was able to simulate what the limit for one hop Sporadic-E from Paul's location might be. One the left above is the approximate range if Paul had a completely flat horizon. The one on the right is the reality.

For Italy, the local hill restricts signals further south than Rome.

For Poland, signals from the east of the country should be easy to hear except the local hill makes things more difficult. Belarus and the west of Ukraine are also more difficult. Notice that that little gap at 90 degrees is reflected in the Sporadic-E footprint.

For the Baltic states and Finland, they should be well within Sporadic-E range but again, the local hill makes things difficult.

It's possible in many cases that some local tropo conditions will extend the footprint further east but overall, the local hills make hearing these areas more challenging.

Example 4: F2 propagation...

As the sunspots increase, there will be weak F2 openings on 28 MHz. Towards the west, Paul should have no problems reaching Newfoundland and Nova Scotia in Canada. With the help of a more southerly second hop, he is well placed to hear signals from well into the USA.

Towards the eastern Mediterranean, the local hill will block some of those signals when the band is just open. Ironically, it may actually be easier to hear signals further away in places like the Arabian peninsula once there is a second hop.

'Up in the air' Values... 

For your own propagation footprint maps, try 360000 for Sporadic-E and 1300000 for F2.

Example 5: Line of sight paths...

The HeyWhatsThat site can also be used to examine line of site paths. The map above shows the path from Paul's location to Clermont Carn in Co.Louth, about 75kms away. This is a major transmitter site for Irish radio stations.

Let's say for example, Paul wanted to get a line of sight path for a contact on the microwave bands. The profile below shows the local hill in the way but there is a location 7kms away that is line of sight to Clermont Carn.

It's not hard to imagine how it might be used for finding suitable paths on the microwave bands or even if someone was just curious if a distant mountain was visible or not.

Other uses... Here's a few...

Portable operation, DX-peditions, Summits on the Air (SOTA) activations, contesting ... are there obstructions in the way? Is your 'perfect' contest location blocked at a low angle on the upper HF bands say to the USA?

In summary... This is a very useful utility to have and the more you use it, you tend to think of other uses.

For the bands like 28 MHz and 50 MHz, short skip can hide the shortcomings you may have in a certain directions. Your horizon profile should make you aware of these and you're looking for no more than 2 degrees.

For the higher bands like 70 MHz, 88 to 108 MHz, 144 MHz and above, tropo becomes a more important propagation mode. This time, you're looking for a very low horizon and the lower the better.

There's a very good reason why people put antennas up as high as possible on the VHF and UHF bands.

Link...
1) HeyWhatsThat website

5000km TEP opening on 144 MHz from Puerto Rico to Brazil - 23rd March 2021

Around the time of the equinox every year, there are long distance VHF contacts made across the equator by means of Trans-Equatorial Propagation (TEP).

This year is no exception and on the evening of the 22nd of March 2021 (early morning on the 23rd in terms of UTC time), the 144 MHz band was open between Brazil and the Caribbean.

The map above shows the FT8 signals heard by WP4KJJ in Puerto Rico.

Txmtr Rcvr Band Mode Distance Time (UTC)
WP4KJJ PY5EK 2m FT8 5198 km 01:20:59
PY5EK WP4KJJ 2m FT8 5198 km 00:24:44
WP4KJJ PU2MBY 2m FT8 4760 km 01:24:29
WP4KJJ PU9DCB 2m FT8 4702 km 00:25:29
WP4KJJ PU9GTA 2m FT8 4672 km 01:21:29
WP4KJJ PT9FD 2m FT8 4666 km 01:51:29
PT9FD WP4KJJ 2m FT8 4666 km 01:28:44
PT9AL WP4KJJ 2m FT8 4660 km 00:23:44
WP4KJJ PT9AL 2m FT8 4660 km 00:23:30

As can be seen from the chart, most of the distances are in the region of 4700 to 5200 kms.

It's worth pointing out that while the times for these TEP openings are around 00:00 UTC, that is about 8pm local time in Puerto Rico.

The TEP opening was also evident on the lower bands like 50 MHz with spots on the DX-Cluster showing paths from Brazil, Argentina and Chile across the equator to the Caribbean, Mexico and Central America.

The Band 2 FM band was also open as reported by the FM DX Brasil account on Twitter.

The map shows the TEP opening at 00:00 UTC with a FM radio station on 103.7 MHz FM on Puerto Rico being heard 5289 kms away in the south of Brazil.

I haven't seen any reports of 144 MHz openings across the equator in Africa and the Pacific. Is it just a lack of stations in the suitable locations? Are stations in the south of Spain and Portugal listening for the 144 MHz beacon on St. Helena???

The DL7APV 8 x 9 Element Antenna Array for Band 2 (88-108 MHz)

One of my interests is listening for long distance radio signals on the 88 to 108 MHz band which is  otherwise known as Band 2 or as simply the FM band to the general public. I recently came across this impressive antenna array from Bernd, DL7APV in Germany.

He is using an array of eight bayed 9-element Band 2 beams mounted on a rotatable base which is normally used for moon bounce on the higher VHF & UHF bands.

According to DL7APV, the antenna array has an impressive gain about about 14 to 15 dBd with a beam width of about 10 degrees.

The individual antennas are the 9-element 3H-FM-9M19 - Modell 2019 from Antennenland which retail at €109 each.

Despite the fact that the antenna has 9 elements, a lot of them are used to make the antenna broadband. It seems to have the same gain as say a narrowband 4 to 5-element Yagi.

For more details on this array, how it goes together and what was heard, check out DL7APV's 3-metre page on his website.

4000km+ opening on Band 2 from Indonesia to SE Australia - 7th Jan 2021

 

Very long distance openings on the VHF bands are always of interest and one such instance happened back on the 7th of January 2021 when Leigh, VK2KRR in New South Wales in Australia managed to log and record several FM Band 2 radio stations from Indonesia.

Normally with Sporadic-E propagation, the maximum distance is around 2300 kms. In this case, VK2KRR heard FM radio stations on the 88 to 108 MHz band from Indonesia, a distance of about 4000 to 5000 kms!

While a number of Indonesian stations were recorded, it looks as if it was difficult to get a positive ID on the exact location for each one. There was however a positive ID of RADIO FBI on the island of Bali on 91.8 MHz and at a distance of  4380 kms.

It's likely that the propagation mode was double hop or chordal hop Sporadic-E. While this is pretty common on lower frequencies like 50 MHz, it is much rarer at the Band 2 frequencies of 88 to 108 MHz.

A full list of videos from the opening on the 7th of January can be viewed HERE.

Columbian radio station on 93.1 MHz heard 4580kms away in Chile by TEP - Nov 2020

Over the last month or so, I've had several posts up on the blog about recent Trans-Equatorial Propagation (TEP) openings on 144 MHz between Brazil / Argentina and the Caribbean. Most of these contacts have been in the range of 4500 to 6000kms. See my 144 MHz page.

Today, I came across a post on a forum about a commercial FM radio station on Band 2 (88-108 MHz) in Columbia being heard in Chile, a distance of some 4580 kms.

Radio Rumba is a radio station in the city of Caucasia in Columbia in South America. It's FM transmitter is on 93.1 MHz and it has as far as I can tell an output power of 5 kW.

On the evening of the 20th of November 2020, Mauricio Toro in the town of Villa Alemana near Santiago, Chile heard Radio Rumba on 93.1 MHz, a distance of some 4580 kms.

Considering that both the radio station and Mauricio were both equidistant from the Geomagnetic Equator, were at right angles to it and the local time was 21:30, the most likely mode of propagation was Trans-Equatorial Propagation (TEP).

Mauricio was using a SONY XDR-S10HDIP receiver with a 7-element horizontally polarised Log Yagi.

Trans-Equatorial Propagation (TEP)

With Trans-Equatorial Propagation (TEP), zones of high ionization occur either side of the geomagnetic equator in the F layer of the ionosphere. What makes the mode so interesting is that it can allow propagation on the VHF bands from 50 MHz to 144 MHz. As the zones of ionization is roughly 400kms above ground level, the propagation paths achieved are in the region of 4000 to 5000 kms, much greater than what might be usual with Sporadic-E.

Links...
1) YouTube channel of Mauricio Toro.

88 MHz Trans-Atlantic signals heard in Ireland - Sun 8th July 2018

This really is a remarkable catch. Paul Logan in Lisnaskea, Fermanagh, Northern Ireland managed to hear a Canadian radio station across the Atlantic at 88 MHz! While 28 MHz and 50 MHz signals are pretty common across the pond, it is extremely rare that signals of such a high frequency get across.

Using a 5 element beam and a SDR receiver, Paul managed to catch CBC radio 1 on 88.5 MHz from Newfoundland, Canada at 22:35 local time (21:35 UTC) on Sunday the 8th of July 2018.

With a distance of some 3200 kms, it is very likely that it was double hop Sporadic-E which is remarkable. It's not that common for the propagation to reach 88 MHz for one hop but to have it at 88 MHz at two spots at the right distance apart is really rare.

The video of the reception is shown below...



Paul has heard trans-Atlantic Band 2 signals in the past but it really is a rare phenomenon. This is only the fourth time Paul has heard a Canadian radio station on Band 2 (88-108 MHz) since 2003. He is the only person to have heard Band 2 signals from the USA.

The only other person to have heard a Band 2 trans-atlantic signal from North America was David Hamilton in Scotland who heard Newfoundland in 2003. Incredibly, a small number have managed to hear Band 2 stations from the Caribbean which is a more southerly path albeit further away.

Paul's website is http://band2dx.webs.com/