Category Archives: Propagation

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 only 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:
Website: http://www.deutschesatlantikwallarchiv.de/radar/germany/rd_.htm
Picture: http://www.deutschesatlantikwallarchiv.de/images/radar/germany/053748.jpg

Addendum November 6th, 2023

Cindy, W2AXO, did a great job in further investigations and published a very comprehensive history of early moonbounce on her website:
https://www.projectdiana-eme.com/the-moonbounce-zeitgeist.html

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.

Addendum:
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.

Conclusions:
Never say no to a sked request
and
NEVER BLAME A HIGH PRESSURE AREA WITH A FEMALE NAME!

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.

Nice Opening tonight

November 29th, 2020

As predicted in the Hepburn forecast, there happened an opening to the west tonight. No really breathtaking distances, but at least three new squares on 2 m (two of them I already worked on 23 cm 😉 ) IN86, IN87 and IN89.

On 23 cm I tried with Grant, G1SDX in IO80FL, first in FT8, but I could only copy him via aircraft scatter due to significant doppler, inhibiting decoding of his signals. He copied me via tropo up to -11 dB, but we had a difference in power of 13 dB (36 element yagi and 10 W vs. 3 m dish and 200 W). So we tried MSK144, where I could decode him via AS, but he had no decodes of me.

It´s a very interesting path, as half of it is over water. It should be an opportunity for combined sea ducting and aircraft scatter. I hope for a chance to try.

Activity as EI8HH is over now

October 21st, 2020

QSOs in October 2020: MS in red, FT8 in green and SSB in blue

While refurbishing our irish home, I found some time in the mornings and the evenings to be active on 2 m. At least I worked 31 squares. Even on 23 cm I got 3 Calls to the log. The rig so far is an IC-9700 with a 7 element yagi and a linear amplifier with 200 W on 2 m and a 69 element yagi on 23 cm,

Now I have to close the station and take the antennas down. It has been a lot of fun and I hopefully will be back next year, if pandemic allows. Many ideas are in my mind now, how to improve the station over here.

Many thanks to Joe, EI3IX, his N adapter female-female allowed me, to run 2 m and 23 cm simultaneously 😉 .

EI8HH on Air

October 2nd, 2020

As some work at our families house in Ireland has to be done, I am spending 3 weeks over here in IO53HN. I got my new IC-9700 with me and have antennas for 2 m and 23 cm. As I have to restrict my movements by government order, no portable activites are possible in the first two weeks. So I will try to work in the UHF/SHF Contest on 23 cm from the southern lake shore of Lough Mask. My favourite direction is to GI/GM. Maybe I can go to a better QTH later in the 23 cm UKAC. On 144 MHz I will focus on meteor scatter in the morning hours.

In a first test on 2 m I worked GI and GM in FT8. GM7PKT came back on my very first CQ. Later I tried meteor scatter with my german neighbour Mathias, DH4FAJ. As he has massive QRM, he couldn´t hear anything, but I copied him twice with +4 dB. So better to try in the morning again.

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.

New Bands down to DC

May 7th, 2020

Yesterday I added a logarithmic periodic antenna for the range 28 to 150 MHz to my little antenna farm. So I am QRV now on the amateur bands from the highest DC band 28 MHz up to 2400 MHz.

Antennas at DJ5AR

Recently I got an IC-7300 with extended frequency range to cover the 50 MHz and 70 MHz, as well as the new Irish bands 80 MHz and 60 MHz.

So I am looking forward to have some cross band QSOs to Ireland soon!

I took down the 3 cm dish for some work on the rig. And I know, the 70 cm yagi is much too close to the new antenna, but I have been too lazy to dismount it.

Addendum May 18th, 2020

First PI4 decodes of EI1KNH in IO63VE on 40 MHz.

AirScout V1.3.3.0 released

May 3rd, 2020

The VHF/UHF/SHF contest on 2nd to 3rd of May was a good opportunity to spend a few hours trying the new AirScout version 1.3.3.0 released by Frank, DL2ALF. In principle it works like it´s predecessors, but is more stable in collecting the aircraft data. My favourite in this case is planefinder.net.

Most impressed I am by the new feature to monitor a number of paths to certain stations simultaneously! This provides more efficiency in arranging skeds, particularly in times like these, when there are a few planes only are available.

Find more details on the AirScout Site.