Video: Modes of Propagation on 50 MHz by K9LA

In June of 2021, Carl Luezelschwab K9LA gave a presentation to the Madison DX Club titled 'Modes of Propagtion on 6 meters'.

There are plenty of guides and explanations about propagation on the 50 MHz band in books and on websites and they tend to be pretty basic. In this video, K9LA looks at propagation modes in more detail and as expected, things are often not as simple as they seem.

It's very easy to look at long distance contacts on the 50 MHz band and just blindly assume it has to be multi-hop Sporadic-E. As you will see in the video, we should all keep an open mind and accept that it may be due to other propagation modes. This is especially true now as the FT8 digital mode is showing that weak signal paths exist that weren't so obvious in the past with SSB or CW.

The 51 minute video can be seen below...

Some timestamps and items of interest...

00:00 to 02:20 Introduction

02:20 to 04:20 Old 50 MHz radios

The talk is then broken down as follows...

Review of all these modes
Antenna considerations
Solar Cycle 25
References

04:50 to 09:30 Fundamentals of the atmosphere and ionosphere.

It's interesting to note that K9LA questions if PMSE (Polar Mesospheric Summer Echoes) at 85kms above the Earth plays a part in bending radio signals slightly before they reach the higher Sp-E and F2 layers.

In the slide for trospheric ducting, there is an error in that it should read 450 metres as opposed to 450 kms. As K9LA observes, tropo ducting at 50 MHz is very unusual in temperate regions.

At 15:45, K9LA talks about SSSP - Short-path Summer Soltice Propagation which is linked to PMSE. It may well be that this propagation mode is responsible for many of the openings from Europe to Japan on 50 MHz as opposed to the standard 'it must be multi-hop Sporadic-E explanation'.

At 27:30, there are charts suggesting that Sporadic-E may be changing over the years.

At 32:00, Carl suggests that equatorial Sporadic-E may be a significant factor where signals are crossing the equator at local noon.

At 36:00, the video looks at Chordal Hop modes. As the image below shows, there can be a lot more going on than just simple hop Sporadic-E...

At 41:00, skewed paths are examined.

45:20 Antenna considerations

46:50 Cycle 25 status

Links...

1) I have some examples of unusual long distance paths on the 6m band on my 50 MHz page.

Guest Post: Propagation Monitoring 2m Band with AIS Data ...by Jörg, DM4DL

Foreword... AIS (Automatic Identification System) is used by ships to identify their location by sending out a signal at 162 MHz which is pocked up by other ships and shore stations. There is a growing community of enthusiasts near coasts around the world who monitor these signals and feed the decoded signals into websites that then display the positions. AIS signals which are a few watts in power act like beacons and can be used by radio amateurs to show if there is any tropospheric enhancement on the VHF bands... de John, EI7GL

Propagation Monitoring 2m Band with AIS Data from Vesseltracker.com ...by Jörg, DM4DL

I'm trying to use the ships' transponders on 162 MHz +/-25 kHz as beacons for the 144 MHz 2m band. My first AIS receiving antenna is on the island of Neuwerk, 15 km from Cuxhaven. 

For 5 years I was able to inspire some HAM radio operators and meanwhile a partnership between the company Vesseltracker and Gabriel, EA6VQ, the operator of DXMaps is planned.

As a test, the Vesseltracker data of some AIS-RX are already being forwarded to DXMaps.

Please check whether you would like to participate in the community with your location?

Example of enhanced VHF conditions in the eastern Mediterranean

The equipment is provided free of charge by Vesseltracker, you can read more here: www.vesseltracker.com/en/community

You are invited to contact David Hewson, the antenna manager in your native language via the Vesseltracker community page, David is from Canada.

Now we are waiting for good conditions, which can be seen in DXMaps under AIS. 

VY73 Jörg DM4DL

Example of enhanced VHF conditions

Video: VHF Propagation Presentation by Jim Bacon, G3YLA

During the current COVID-19 pandemic, the Mid-Ulster Amateur Radio Club are continuing with their successful Tuesday night lecture series. Recently, they had an interesting talk on VHF Propagation from meteorologist Jim Bacon, G3YLA.

Video...

The video above can be broken down as follows...

00:00 to 07:00... Introduction

07:00 to 10:25... GB2RS VHF Propagation Report - A brief outline of how the weekly bulletin is put together for the RSGB news.

10:25 to 28:30... Tropospheric Propagation - In this section, Jim covers elevated and surface ducts as well as the best time to watch any high pressure weather systems.

28:30 to 1:12:30... Sporadic-E - This section covers meteors which are the fuel for Sporadic-E and the various trigger mechanisms like atmospheric gravity waves due to mountains, thunderstorms and changes in the Jet Stream.

1:12:30 to 1:13:50... Rainscatter - This mode of propagation at microwave frequencies is briefly covered.

1:13:50 to 1:21:20... Propquest - Sporadic-E prediction website

1:21:20 to 1:23:30... Pulling it all together - GB2RS VHF Propagation Report

1:23:30... Q&A

Calendar for F2 openings on the 11m and 10m bands

For anyone using the 27 MHz to 29 MHz part of the spectrum, propagation is an important subject especially if you want to get work stations around the world. In general, the two main modes of propagation for the 11m and 10m bands are Sporadic-E mainly during the Summer months and F2 for the rest of the year.

In this post, the charts deal just with F2 and what parts of the world are likely to be heard at certain times of the day throughout the year.

It should be noted that this is a general guide. It is highly dependent on where we are in the 11 year Solar Cycle and what the Solar flux is. Usually for stations in North-West Europe, the Solar flux needs to be about 80 or above to start getting openings. North-South paths are more likely and the East-West ones appear with higher flux levels.

The big variable in this is Sporadic-E. This occurs mainly during the Summer months but is present during most months to a certain degree. This can allow stations in the UK for example to get into the Mediterranean on Sporadic-E and then via F2 into South Africa. Expect the unexpected on 10 metres.

This map shows various parts of the World numbered and the charts are based on propagation from the UK and Ireland.

The charts below show the times of day those are might be heard at various time of the year.

Skewed path on 28 MHz???

This morning (~8:45 UTC), I heard NH7O in Hawaii on SSB on 28 MHz.

His signal was very weak, maybe 4/1 to 4/2 at best. He was working a pile up and it was obvious that he was getting into the UK and Ireland pretty well. I gave him a call towards the end......managed to get a EI7?? back but then he dived into the noise. I think it was probably just at the end of the opening.

But I was curious. How did the signal get from Hawaii to Ireland?

This is the short path shown above. It almost certainly wasn't short path as the band hadn't opened to the US and the North-West yet. What about long path? Did the signal travel over the South Pacific, over Antarctica and then over Africa???

Or was it a skewed path? From somewhere over the Indian Ocean? I have heard of this before whereby European stations work Japan on 50 MHz by beaming at the Indian Ocean. Not long after hearing NH7O, I could hear the Australian beacon VK8VF/B near Darwin. Earlier, I was hearing the Phillipines on WSPR so the band was certainly open to that part of the world.

Wonder what way people were beaming when they worked him? It's kind of hard for me to tell with my vertical ;o)