Category Archives: Tropo

Windmill Scatter

August 30th, 2017

As the weather forecast promised heavy thunderstorms for today, I was looking out for scatter points on 13 cm. Pointing to eastern France, I found a heavily scattered signal of DB0UX in JN48FX in 204°.

But the sound was quite strange and rhythmic. When taking a look out of the window, I saw the dish pointing at two windmills in 1 km distance.

This kind of scatter is not very helpful, but a nice experience anyway.

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!

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:


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

Another strange constellation (Update)

February 6th, 2014

While performing my beacon check on December 16th, 2013 at 8:30 UTC, I stated that all beacons seemed to be at a normal level. Except, when looking for DB0FGB (JO50WB) with the dish heading 85°. There was a constant carrier of about 20 dB 15 kHz up, keying F1ZBK (JN38BP). Expecting a big signal, I turned the dish to France. But the beacon was only 15 dB with QSB, when beaming directly to it at 228°. Then I turned the dish back to 85° and noticed, that HB9EME (JN37KB) joined the party.

2013-12-16 09_30 F1ZBK HB9EME 85deg

DB0FGB, F1ZBK and HB9EME with dish heading 85°

The rain radar didn´t show anything unusual and the F5LEN Refractive index forecast for Europe promised only marginal tropo conditions for this area. Only DL7QYs Condition Index for south Germany has been on a level of 7 (1 = poor; 10 = extreme).

2013-12-16 09_00 F5LEN index

F5LEN Refractive Index

DB0FGB was a bit above normal at about 15 db with little QSB up and down. F1ZBK was constantly at 20 dB, when beaming 85° and around 15 dB with QSB heading 228° (direct). HB9EME was up to 20 dB in 85° and peaking 15 dB in fast QSB when beaming 198° (direct).

Green: Paths from Mainz to the beacons
Orange: Paths of the beacons to the area of the supposed reflection point

I checked HB9BBD, F5ZBS, F1ZBI and others, but couldn´t see any similar effects. The angle was very small. When turning the 3 m dish 5° left or right, the signals disappeared. These conditions lasted for about one hour.

Path DJ5AR to DB0FGB (by AirScout)

Topographic profile between DJ5AR and DB0FGB

The horizon in 85° is about 80 to 90 km off. A plausible explanation could be a strong troposheric duct between the beacons and a reflecting topographic formation.


In issue 2/14 the german magazine “Funkamateur” published an article by Matthias Hornsteiner, DG4MHM “Prognosekarten für troposphärische Überreichweiten” (Prediction maps for troposheric ducting). Matthias explains the basics of ducting and analyses the models, the well known refractive index maps of F5LEN and W. Hepburn are basing on.

So I had the intention, to ask him about a possibility for a reconstruction of the wheater constellation of that day. I have to thank him very much for his comprehensive answer.

As Matthias explained, the situation, shown on the map, was quite common for this, as he describes it, “anti-winter”. But it holds the possibility, that warm air might glide onto cold air at ground level. And indeed, when he reviewed the data of weather balloons launched at Stuttgart on that day, he found indications for a strong inversion in an estimated level of 400 to 600 m over south Germany. That matches!

In a distance of 200 km from here, the the topographic profile shows a formation, high enough to reach the level of this duct, as well as the mountains of the Fichtelgebirge do, where DB0FGB is located. The distances from Mainz to the area of the supposed reflection point is between 200 and 250 km. From F1ZBK and HB9EME it varies between 400 and 500 km. So the total path should have been between 600 and 750 km.


Strange Conditions

December 11th, 2013

It is funny to check the beacons tonight. Most remarkable are two constellations, shown below:

2013-12-11 21_59 DB0VC and DB0AAT

While looking for DB0AAT in JN67HU, DB0VC in JO54IF could be received too. When beaming to Kiel, DB0VC can be heard even on 2320 MHz. It is beacon #9 on 13 cm.


2013-12-11 22_23 DB0NCO beats DB0FKS

DB0NCO beats Frankenstein

From my QTH DB0NCO has the same bearing as DB0FKS. The location of DB0FKS, the  Frankenstein Castle, can be seen visually from here in a distance of 34 km. DB0NCO is 203 km away but tonight it is stronger than DB0FKS, when coming up in QSB.

Opening September 21st 2013

September 21st, 2013

While performing a last beacon check before going to bed and all local beacons were quite normal, I took notice of a weak carrier 1 kHz up of F1ZBK on 1296.855 MHz. After optimizing the antenna and using a narrow filter I heard EA2TZ in IN93BF over 1073 km for the first time ever.

2013-09-21 20-50 EA2TZ

Left signal: F1ZBK/B, right signal: EA2TZ/B

 EA2TZ/B as received by DJ5AR over 1073 km on 23 cm

After posting this information in the ON4KST chat, Matej, OK1TEH sent the phone number of EA2TO and told me that Javier is currently QRV on 23 cm from IN83. After exchange of a few SMS he came back on my CQs and we could complete a QSO: A new DXCC, a new square and a new tropo ODX of 1173 km on 23 cm!
When closing down the station I had a quick look on 70 cm. There he was again: EA2TO in SSB. We had a nice chat and for me: A new DXCC, a new square and a new ODX of 1173 km on 70 cm!

Only 2 QSOs tonight, but I am very happy with it.

Beacon check

March 13th, 2013

There are some beacons I am used to check whenever I am in my shack. One of them is quite a special one: DB0LTG on 1296,745 MHz.

This beacon provides a very stable signal of normally 40 dB, usable for antenna calibration, especially when the sun isn´t available at night time. On the other hand the beacon is part of a linear transponder located on the Unnenberg near Gummersbach, Germany. The input is in the 432 MHz band and the output in the 1296 MHz band. In my SDR I can even see the noise floor of the transponder next to the beacon.


DB0LTG with noisefloor

When talking about the transponder, Rudi, OE5VRL/5 was the only one I worked on it until now. We had big fun in performing a QSO via DB0LTG in October 2012 when conditions allowed such a crazy test. While performing my daily beacon check tonight, I noticed some SSB signals on the transponder. So I prepared my (poor) 70 cm equipment and set it to the input frequency. My first call was heard and so I enjoyed chatting to the guys who were initially setting up and now using this nice toy every Wednesday night.

By the way: The distance from Mainz to Gummersbach is 135 km. For details of transponder and beacon visit the website of DB0LTG.