Tag Archives: Tropo

Tropospheric Ducting

June 3rd, 2023

In Spring 2022 I installed a new antenna system for 2 m, 70 cm and 23 cm at my second home in Ireland. In the last days I could experience an long duration tropospheric opening to the continent. On May 23rd I noticed a large ducting area to the north, shown in the Hepburn Tropo Index. Not really expecting something, I turned the antenna northwards and was surprised to hear OY6BEC in IP62mb over 958 km with 529 on 2 m. It could be monitored most of the time until June, 2nd. Even on 70 cm it could be heard from time to time, but nothing on 23 cm, even when it peaked up to S9+20 dB on May 28th. I contacted Regin, QY1R and Trygvi, QY4TN, for skeds on 2 m, but unfortunately no signals could be detected. The two stations are quite close to sea level and the beacon is located on Mt. Sornfelli, 745 m asl.

From May 13th to May 28th I had a couple of contacts in the range, aircraft scatter allows. Beside the 2 m QSOs (green), I had some on 70cm (blue) as well. I worked the local lads on 23 cm (red) and had a QSO with Martin, GM8IEM, as I had promised him to arrange a sked, as soon as 23 cm is up and running. On May 26th a short Es opening happend and I could work Paolo, IK7UXW, with whom I had a couple of QSOs and tests from home in Mainz on 23 and 13 cm via a combination of tropo and aircraft scatter propagation.

On June 29th the reach extended by tropo to the costal area from northern France to the west of Germany. ODX of the day was Günter, DG6JF/P, over 1105 km.

As the propagation conditions went to normal for me on May 30th, the next day, May 31st, startet with QSOs to Denmark on 2 m (green) and 70 cm (blue). Around noon the duct extended to the very north of Germany. ODX of the day was Oliver, DH8BQA, JN73ce over 1559 km. The duct seemed to be very narrow, as Chris, SM6VTZ, and Steffen, DD0VF, could only be worked via meteor scatter (yellow).

The duct moved southwards on June 1st with many stations from Belgium, the Netherlands and Germany. no more DX contacts were made on 70 cm, just the 2 m band was open for me. ODX of the day was Uwe, DL4DWA, over 1559 km, followed by Peter , DL3JIN over 1542 km.

And again the duct moved southwards on June 2nd and calmed down around noon. ODX of the day was Gerhard, DK1FG, over 1459 km with an outstanding signal, just, as I am used to, when QRV at home in Germany.

Fun fact: When I turned my antenna to the north in the early morning of June 2nd, OY6BEC over 980 km was still there. Turning the antenn to the east, I could hear DB0HRF, JO40ff, over 1276 km. It is located on the Feldberg, as close to my German home, that I can see the mountain out of the window of my shack.

Tropo to Belarus this Morning on 144 MHz

September 9th, 2020

A nice inversion could be seen out of the window of my shack this morning, promising good conditions. In fact I have been a little too far south for the duct, but at least I had two QSOs to Belarus in FT8.

Green: worked – Red: heard via tropo – Blue: heard via meteor scatter

The stations worked and heard via tropo have been in distances up to 1300 km. Occasionally signals appeared from more distant stations, 1500 and more km away. These could be decoded in one or two periods, then disappeared. Some reappeared later in the same manner, so it´s very likely, it has been meteor scatter, as it happened in the early morning, when conditions are good for sporadic meteors.

Worked Hrd Tropo Hrd MS 

A digital evening on 23 cm

October 25th, 2017

There was nice activity in JT9F on 23 cm tonight. It seems this mode works fine with aircraft scatter. I first worked Conrad, PA5Y in JO21VO (255 km) and Sam, G4DDK in JO02VO (540 km) via Tropo. Then logged a QSO with Neil, G4BRK in IO91HP using mainly aircraft scatter. In another test I decoded Neil, G4DBN in IO93NR (756 km) by reflections on airplanes. PA0JME and ON5KTO were calling CQ, but not replying to my calls. Instead I worked John, G4BAO in JO02cg (619 km) in an (too) easy way.

Worked stations in green, the heard ones in blue.

Anyway, it was a promising and exiting evening!

Addendum October 27th, 2017

Yesterday I logged Rien, PA0JME, Wim, ON5KTO and John, G4ZTR, also in JT9F on 23 cm.

Chatting with John, G4BAO, last night, I learned, he recently initiated a “Digifest” on the microwave bands every Wednesday. This resulted in what happened two days ago. In my opinion it´s a very good idea to have such an activity evening beside the regular contests.

Disappointing Morning / Amazing Evening

August 17th, 2017

The whole morning I monitored EA2TZ/B in IN93BF on 1296.854 MHz over a distance of 1072 km, peaking up to 30 dB. The vertical profiles of 0:00 UTC from Paris and Bordeux showed an inversion at 1000 m altitude. F6DKW from Paris was booming here, but nothing could be heard of beacons close to the path or in tests with F6CIS, IN94WL and F6AJW, IN93EK. The duct was just too high.

Tonight Paolo, IK7UXW, JN80XP, asked me in the KST chat, to give it another try. We had discussed the possibility of combined propagation with aircraft scatter and tropospheric ducting before.

The path is perfect, as there is one hop over the Alps and a plain track over the Adriatic Sea.

On Tuesday last week, while I was watching the other Paolo aboard the International Space Station via HAMTV on 13 cm, Paolo had initial QSOs in this propagation mode with Daniel, DL3IAE, in JN49DG on 23 and 13 cm. That was a great effort! So I was more than poised for a try.

Paolo has a 2 m dish and QRO, so he started calling me in CW. I heard “musical noise”, EMEers know, what I mean, with very strong bursts from time to time, lasting for some seconds. After a while we decided to try in JT65c. And from the start I could decode Paolo in most of the periods.

The better decodes always correlated with airplanes, crossing the path within a specific window soutwest of Munich defined by a path with a virtual end at the coast of the Adriatic Sea.

Most impressive was the crossing of an A380-800

At the end some bursts could be seen again (after 30 seconds)

The whole Test took almost an hour to complete, as my TX power is about 10 dB less than Paolos. It is evident that JT65 with 60 second periods is not very useful.

Paolos reference for ducting on the Adriatic Sea is IQ3ZB/B. Tonight it was at S9 + 30 dB. With good conditions it can be at S9 + 60 dB. So we agreed in continuing the tests in other  digital modes and in CW as well as on 13 cm.

Nice Tropo this Afternoon

December 20th, 2016

There is some nice troposheric propagation this afternoon. It looks promising for the NAC, IAC and UKAC this evening on 23 cm. When looking for DB0XY I saw this situation:

2016-12-20-14_00-23-cmHopefully it will last for some hours!

Testing the new Kuhne MKU 23 G4 on 13 cm

November 22nd, 2016

Today I configured the MKU 23 G4, I ordered from Michael in Friedrichshafen to perform a RX test. Via aircraft scatter it was no problem to receive the beacons OZ7IGY in JO55WM over 670 km and OK0EK in JN89VJ over 689 km. The sun noise is at a level of 6 dB.

ra-maps-jn49cv89kf-2016-11-26-07-21Beacons regulary receivable on 13 cm (green: TR / blue: AS)

The motivation is high now to configure the TX line as well 😉

Strange Tropo today

September 28th, 2016

During the morning I was able to monitor GB3FM in IO91OF on 1297.050 MHz and G8MBU in IO90IR on 1296.800 MHz. Now in the afternoon F5ZCS in IN87PT on 1296.959 MHz came out of the noise with a strong signal of 549 with fast QSB. It is my 53rd beacon on 23 cm. The weather here in Mainz doesn´t look like tropo: 8/8 cloudy and wind at 40 km/h.


Listen to F5ZCS:


DL65DARC will be QRV on 23 and 13 cm

June 15th, 2015

From Monday, June 22nd to Wednesday, June 24th I will be QRV during the evenings on 23 cm and 13 cm using the special event callsign DL65DARC.
Skeds (aircraft scatter, tropo) are welcome via ON4KST, Facebook or email.

Rig will be a 3 m dish with 150 W on 23 cm and 75 W on 13 cm. The QTH locator is JN49CV. SSB, CW and WSJT modes are suitable. Operation on relays is not intended.

If I find some spare time, I will be QRV on June 25th, 26th and 28th as well.

On Saturday, June 27th, you can meet me in Friedrichshafen.


Opening February, 10th and 11th 2015

February 12th, 2015

The first remarkable opening for quite a long time happened from 10th to 11th of February 2015. F5LENs refractive index forecast promised good conditions for these days. It started with some stations from G, appearing on 2 m. While the activity contests were going on in Scandinavia and the UK on 70 cm, a few operators dropped into the microwave chat. At least two new DXCCs could be worked before going to bed: Steward, GM4AFF in IO86TS and Gordon, GI6ATZ in IO74AJ as no. 30 and no. 31 on 23 cm. Only a few beacons could be heard via tropo: GB3FM in IO91OF, GB3MHZ in JO02PB, PI7ALK in JO22IP, OZ5SHF in JO45VX and OZ1UHF in JO57GH as a new one.

Green: Stations worked on 23 cm Red: Beacons heard on 23 cm

In the morning the inversion had moved to the north-east and never before heard beacons from Sweden became audible on 23 cm. SK6UHI in JO57TX, SK6MHI in JO57TQ, SK6UHI in JO97CJ and SK4BX in JO79LI over 1138 km as my new beacon ODX appeared on the band. Many of the Swedish stations were as loud here as locals. Some of them could be worked on 13 cm as well.

Chaos on 1296.942 MHz!

November 28th, 2014

2014-11-28 10_13_55-OK0el vs DB0AJA

There are good tropo conditions to the east from here for quite a while. I worked OK1MAC on November, 26th with an outstanding signal. OK0EA, SR6LHZ can be monitored constantly. I missed OK0EL on 1296.940, but solved the miracle today. The frequency shifted to .942 and the signal has been covered by DB0AJA. It´s nice to listen, how OK0EL in 526 km distance is battling against nearby DB0AJA,131 km away. As can be seen, DB0AJAs signal is accompanied by several dopplershifted reflections on airplanes.


It is interesting to see, that F5LENs refractive index as well as Hepburns tropo index don´t really illustrate the real conditions today. The conclusions is: Always perform a beacon check before switching off! The result may be surprising.

2014-11-29 09-00 F5LEN DJ5AR OK0EL