Successful contact on the 1296 MHz band by bouncing signals off Geostationary satellites - Jan 2025

I recently came across details of this remarkable contact on the 1296 MHz (23cms) band.

On the 22nd January 2025, the PI9RD station at the Dwingeloo radio telescope facility in the Netherlands managed to make a contact with HB9Q in Switzerland by bouncing signals off an INMARSAT satellite in geosynchronous orbit.

While it is reasonably common for stations on the 1296 MHz band to bounce signals off the moon and for geostationary satellites like QO-100 to relay microwave signals, the signals on this occasion were physically bouncing off the metalwork of a geosynchronous satellite.

When you consider that satellites in a circular geosynchronous orbit are at an altitude of 35,786 kms rather than a few hundred kms for satellites in low earth orbit then it's even more remarkable.

Jan, PA3FXB gave this account of the contact...

Today at PI9RD (25m Dwingeloo telescope) we succeeded in completing two QSO’s on 23 cm with HB9Q via reflection off geostationary satellites. 

This journey started in May 2013 when Andreas DJ5AR and I (PA3FXB) had our first 23 cm ISS bounce QSO using our 3 m dishes. We started experimenting with the big dish using smaller satellites.

In 2016 we (DJ5AR and PI9CAM) had a QSO via reflection off an old orbiting weather satellite. Since then, we started thinking of a QSO via reflection off a geostationary satellite. Much much, farther away but virtually fixed so no tracking challenges. 

With HB9Q we tested using a cluster of ASTRA satellites using the double tone of JT65. We did not hear or see anything, but computer analysis showed that the signal was there! We did it again and got the same result. People familiar with the satellite world suggested us to use INMARSAT as passive reflector. 

120W into a 25m dish on the 23cm band

The first INMARSAT-test with HB9Q was at the end of 2023 and produced a nice stable -23 dB and decoding signal on our screen. We then used Q65-120A. Our output power is much less so Dan did not see our signal and a strange thing happened: After a few minutes the signal disappeared….

Thinking about this and talking to satellite operators brought us to the conclusion that the orientation of the solar panels of the sats is an important thing to get good reflections. Nobody could tell us how it works on the different sats but there appear to be two systems. Constant moving of the solar panels and moving them in big steps every now and then. This might have happened when the reflection disappeared…. 

With this uncertainty about the solar panel position we decided to simply try a few INMARSATs. Today was the day ??

We started with the same INMARSAT GX5 we used in 2023 and we immediately saw -21 dB signals from Dan. This time we used Q65-60A to save our SSPA’s. After calling several times we received R-32 from Dan! Thanks to averaging!

And some minutes later after sending our RR73’s several times we received 73 from Dan. So, we made it!!! Just barely but we made it ?? 

Then we decided to try another sat. We went for INMARSAT 4A F2 (Alpha) and we experienced much stronger reflections! -15 / -24 dB. Dan was speaker copy in Dwingeloo! We had an ‘easy’ QSO?? 

After that we tried two other INMARSATs but with no result at all. So, here we are, two QSO’s via passive reflection off two INMARSATs. We think this has never been done before by radio amateurs. 

It made us very happy! Thanks to Dan and his patience and many tests! 

***

Well done to all concerned. For some details of other interesting contacts on the 1296 MHz band, see my Microwave page.

Amateur TV signals from the German Antarctic Research Station DP0GVN

After hearing the German Antarctic research station, DP0GVN on 28 MHz WSPR yesterday, it reminded me of a recent story I saw about how that station is also operational on ATV (Amateur Television) on the QO-100 Geostationary satellite.

The QO-100 geostationary satellite is located over central Africa and it is allowing radio amateurs the opportunity to experiment on the microwave bands. The uplink to the satellite is just above 2.4 GHz while the downlink is just below 10.5 GHz.

The footprint of the satellite with 5 degree and 10 degree elevations is shown above. For the DP0GVN station in Antarctica, the elevation of the satellite is about 7 degrees above the horizon.

AMSAT-DL recently paid for a new antenna and radome to be installed at the station as shown above. This happened at the start of January 2022.

This is the new radome in place to protect the antenna from the harsh Antarctic weather.

This video clip from Vale, IZ5ILX in Italy dated the 31st of January 2022  shows the ATV signal from DP0GVN via the QO-100 satellite.

Excellent DVB-S2 tests from NEUMAYER STATION
ANTARTICA VIA P4-A - QO-100 GEOSAT
QRG: 10497.750 GHz 1,5 MSr -2/3 Fec#DP0GVN @amsatdl #QO100 #ANTARCTICA
📡📺📹🛰️ pic.twitter.com/DF1Hr6Hwv8

— IZ5ILX Vale (@iz5ilx) January 21, 2022

While I'm not that interested in Amateur TV or satellite operations, I did find this story interesting because it shows how a geostationary satellite like QO-100 is opening up a lot of possibilities for experimentation on the microwaves bands and with Amateur TV.

For someone outside the footprint like in North America, these experiments are impossible unless they live near others active on those bands or modes.

There has been a lot of talk of late about how to get more people interested in Amateur Radio. I'd suggest that experiments like this are going to appeal a lot more to a younger generation than say making SSB contacts on the HF bands which is rather dated at this stage.