Moonbounce by Accident in 1943

September 27th, 2023

I have been in contact recently with Cindy Stodola Pomerleau, W2AXO, the daughter of Edwin K. Stodola, chief scientist of project Diana, about a text by Dr. Stepp, an engineer of the German Telefunken company, describing reflections from the moon with a radar system in 1943. The text has originally been published in a german nautical journal and been reprinted in CQ DL later. So it is in German and as I think it could be of some interest to the moonbounce community, I did a quick translation to English.
Btw.: If interested in Project Diana, the book, written by Cindy, is a must have!

Not much is known about the German technicians picking up reflections from the moon, while testing newly developed radar equipment on the island of Ruegen. Later one of them, Dr. Stepp, published a short report, he wrote:

Back in 1943 Telefunken was to develop a system for detection and measurement of near to ground targets – ships, low-level attack aircrafts and vehicles – with a maximum outreach.

The mission to detect close to ground objects required among high transmission power and receiver sensitivity the use of least possible short waves. As the capabilities of those times allowed, a stationary facility was erected with the following characteristics:

TX pulse power:                  120 kW
Pulse duration:                    1,5 µS
Wavelength:                         53 cm, abt. 564 MHz
RX sensitivity:                      12kTo
Antenna surface:                45 m²
Polarization:                         horizontal
Number of dipoles:            8 per row horizontal
                                          80 per column vertical

The antenna could be turned around the vertical axis. It had a very narrow vertical beam with zeroes in the diagram 1.3° beside the main beam direction.

The system was named Wuerzman. In late 1943 the system was erected in the south of the island of Ruegen on a hill called Bakenberg for field testing.

The results confirmed the reckoned outreach: Ships of mid sizes could be detected up to the horizon at about 50 km, airplanes up to a height of 1000 m and up to a distance of 100 km. Under convenient weather conditions it detected targets in the harbor of Danzig (Gdansk) and the Gulf of Finland.

After the first tests I instructed Willi Thiel, a high-achieving technician, to mind the system by himself and to operate it continuously. A couple of weeks later I returned to the island of Ruegen for tests nearby Goehren. On the last day of my stay, a couple of hours before my journey back to Berlin, I visited the Bakenberg again. The sky was very cloudy and the night extremely dark. On our way to the Bakenberg W. Thiel told me about a strange fault, he mentioned the day before at the same time, but couldn´t find the reason, as after about two hours it gradually declined and at least disappeared.

After starting the operation of the Wuerzmann I made following observation: The fault appeared again, it had a length of several pulses and a bigger pulse amplitude than the strongest close targets. It appeared about two seconds after the start of transmission and disappeared pulsing analogous later after the stop of transmission. All other targets disappeared in the moment of switching off the transmitter. The fault happened only when the antenna beamed east, disappeared at once after larger changes of the bearing and appeared with a two seconds delay when beaming east again. It seemed, we targeted the moon behind the clouds. The degrading disappearance I explained as the slow movement of the reflecting body out of the narrow horizontal pointing beam together with a growing height over the horizon.

Soon after the system went into destinated operation, I never heard of further observations.

German original in: Der Seewart, Band 35, 1974, Heft 2, S. 71
Reprint in CQ DL 1979, Heft 7, S. 328
Translation by Andreas Imse, DJ5AR

A picture of the system can be found here:

Wiolas last Farewell

June 8th, 2023

It seemed, last weeks openings, brought to us by high pressure area Wiola, had been coming to an end, but at least it was back again.

After finding a simple fault in my IC-9700 I was able to receive as usual and worked stations from Germany, the Netherlands, Denmark. I heard SM7DTT calling CQ and working some stations from UK, but he didn´t copy me. Around midnight it calmed down and PA2M on 70 cm was the last QSO.

The early morning started with Germany again and Sweden was there as well and could be worked even on 70 cm. ODX on 2 m was SM6LPF in JO78CK over 1555 km, on 70 cm SM6VTZ, JO58IJ, over 1412 km followed by SM6CEN, JO67AJ over 1409 km. But the fulminant final was brought to me by Kjeld, OZ1FF, with a QSO on 23 cm. It took a lot of patience, but at least we did it.
Thank you Kjeld!

As in the previous openings I kept an eye on 144.300 MHz, called there a couple of times in SSB, but no sign of live in analogous modes. So all QSOs were done in FT8.

NB: QSOs on 2 m in green, on 70 cm in blue and on 23 cm in red.

Tonight Brian, OZ7SKY, requested a FT8 sked for 70 cm in the ON4KST chat. I was pretty sure, the condx were completely gone here in the west of Ireland. But I am used to give even the crazy things a chance and as the computer is doing the job, I agreed and could decode hin at once. During the first twenty minutes we had no more, than an nice chat on KST and me telling him the level I received him. The deep QSB on his signal was between -20 and -06, when he got my report and another 15 minutes later the relief: My RRRs.

While I am writing this, my PC decodes signals of OZ2OE and OZ4VW at low levels on 70 cm. As some CQs on 2 m, after working two GMs, didn´t find any takers, I closed down the station now.

Never say no to a sked request

Tropospheric Ducting at EI8HH

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 a 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 2 m 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 in the past.

On May 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, JO73ce 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 antenna 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.

FR5DN/B 144 MHz TEP Beacon on Reunion

February 6th, 2023

Phil, FR5DN, is running an experimental beacon on 144.245 MHz beaming to the eastern Mediterranean Sea. It is located on the island of Reunion in LG78qs. The antenna is a 13 dB yagi, horizontal polarized at 7 m above ground, running 80 W. He will operate it in CW, when he is at home, mainly from 16:00 to 18:30 UTC.
The operation will be announced on DX Summit and in the ON4KST chat. As he transmits continuously, feedback may be sent in the chat or via his email address on

FR5DN/B beaming towards the Mediterranean Sea
The geomagnetic equator is shown in green

He already tried years ago, but got inspired by the TEP events that happened recently in South America and hopes for monitors in Europe to gather some experience in this propagation mode.

Nice Morning Inversion

August 2nd, 2022

As the Hepburn Tropo Index predicted some ducting over northern Germany and the Baltic Sea for todays morning, I checked the beacons on 23 cm. DB0VC, JO54if, 509 km, was strong on 23 cm as well as on 13 cm, but nothing on 3 cm. I went on with the OZ and LA beacons and found OZ5SHF, JO45vx, 685 km and LB2SHF, JO48ad,917 km, with booming signals. Unfortunately there was no one QRV in Scandinavia.

Then I called in FT8 on 2 m and got some response from Denmark and Northern Germany. Surprisingly I got called by UA2FBW, KO04ir, 1002 km and much more surprised I have been, when I saw in the DX cluster, that EA5GJ, JM97jw, spottet me as well at the time, I worked Igor. Might have received me by some Es or MS, while beaming northeast.

With the rising sun the beacon signals on 23 cm became weaker and weaker and disappereared at least. The same happened to the DX stations on 2 m.

QSOs on 2 m in green, all in FT8. Received beacons on 23 cm shown in red.

New Antenna System at EI8HH

June 4th, 2022

When going to Ireland in May, I went with a trailer and could take a pneumatic mast and some antenna stuff with me. So I setup a 2 x 7 elemt yagi for 2 m, a 15 element yagi for 70 cm and a 67 element yagi for 23 cm. The rotator is a Spid BIG-RAS/HR, so elevation is possible as well. There are SHF-Electronic LNAs at each antenna and Gemini linears with 200 to 300 W driven by an IC-9700.

On 2 m I could log a couple of QSOs in FT8 (blue) and SSB (green) so far and have been lucky to use some tropo to France on May 27th and 28th (F6DBI, IN88ij, 716 km and F8BON, IN86wv, 903 km) and Spain on May 28th (EC2BBS, IN93bi, 1262 km).

Digital Activity on 23 cm

March 16th, 2022

Last January the QSO BANAT Association added a 23 cm section to their VHF-UHF FT8 Activity contest, open to all digital modes. Tonight it was the 3rd round in this year and my second time in participating. In February I struggled with FT8 and some QSOs could have been much faster completed by using CW, as the one with Roberto, IK2OFO, whom I worked many times before in CW on 23 and 13 cm.

QSOs in the Digital Activity Contest on 23 cm: FT8 in red and FT4 in green

This time I tried FT4 in some skeds and was surprised by the excellent performance of this mode. Of cource I tried with Roberto and it was as fast as in CW. Later at the end of the contest I had QSOs with Andre, DL6AST, in FT4 on 23 cm and on 13 cm as well. After that we tried MSK144 and JT9f (my favourite so far) on the higher band, but without success so far.

It seems FT4 is more robust in handling the varying doppler shift and multipath propagation caused by airplane reflections compared to FT8.

Many thanks to the friends of the QSO BANAT Association for organizing this activity on 23 cm and not dedicating it to FT8 only. This opens space for experimentation, the heart of amateur radio!

First steps on 24 GHz

February 26th, 2022

After my visit to Berlin a fortnight ago, where Thomas, DC7YS, granted me massive support in assembling my 10/24 GHz duo band rig, I have been out today to give it a try in the BBT contest.

The selected location is a building in the vine yards just a little south of my home.

It has a terrace upstairs with a perfect view to the horizons.

Despite beeing an asolute newbie, I logged two QSOs. The first one I had with Martin, DL3SFB/p on the Hornisgrinde in the Black Forrest near Freiburg. Signals were just good enough to complete in SSB over 144 km. Second was Daniel, DL3IAE, near Landau, 70 km away.

Daniels signal was extremly distorted by windmills and even in CW very hard to copy.

A test with Ewald, DK2DB, in Karlsruhe was not successful, because of a pear tree obstructing him in my direction.

The grey box houses latest Kuhne transverters for 10 and 24 GHz, driven by an IC-705. Output after all the lossy semi rigid and relays is measured to 6 W on 10 GHz and 1 W on 24 GHz. The feed a dual band horn, made by Paul, W1GHZ. The size of the dish is 80 cm. Power sources are batteries of my Makita tools.

After the Test with Ewald I decided to leave, because some strong gusts came up and the dish has a quite a good wind load. As the stuff is very heavy, the tripod is too fragile to withstand the weight plus the wind.

DB0KK: Visit at DC7YS´s Microwave Beacons

February 13th, 2022

Today Thomas,DC7YS, took me on a sight seeing tour to the Teufelsberg, a former US military facility and then straight through President electing Berlin to his beacon location in the east of Berlin.

DB0KK, as seen from the Teufelsberg in about 16 km distance.
Teufelsberg, as seen from DB0KK
Thomas, DC7YS, with the beacon antennas to his right. It is located on a 21 storey high rise building in Berlin-Lichtenberg, JO62RM76.
Beacons on a turnable pole with a camera on top to check the correct direction. Thomas can turn it on demand by request. 76 ghz on top, 24 GHz beneath and 47 GHz on the back.
24 GHz beacon
24,048.850 MHz
0.5 W
10 dB horn antenna

47 GHz Beacon
47,088.850 MHz
0.5 W
10 dB sector antenna

76 GHz Beacon
76,032.850 MHz
0.27 W
10 dB sector antenna