December 2015: elevated SUI ducting

The beginning of December brought an unexpected tropospheric propagation. The weather was influenced by high pressure and it was rainy. In the evening on December 2nd, 2015 I noticed some distant signals. When I checked my tuner remotely, FM4 from Salzburg was already at stereo + RDS level. In just a hour I also heard Wendelstein, Hornisgrinde, Bregenz, Grünten, Säntis and the furthest location – Rigi @ 1015km, which I logged for the first time.

This recording also includes a comparison with the webstream at 00:04. Thanks to bad local propagation conditions I easily attenuated RMF FM signal from Piła/Rusinowo on the same frequency as 96.6 SRF 2 Kultur.

Tropo from Switzerland is quite rare here in Poland, because mountains ranges on the Czech Republic border are obstructing this direction. However, Säntis ducted once before in 2011 and the signal reached RDS level at peak! This time tropo was weaker and patchy, except Salzburg with quite strong, but also unstable signal.

Bregenz recordings are included in my log: Bregenz – Pfänder, Austria (908 km).

December 2, 2015 – logs:

UTC MHz Station ITU Location ERP QRB Details
1917 104.6 FM 4 AUT Salzburg/Gaisberg 100 712 A213 __FM4___
1920 101.8 Antenne Salzburg AUT Salzburg/Gaisberg 10 712 jingle ID 23dBf
1926 88.7 Bayern 2 D Grünten (Allgäu) 100 876 15dBf
1935 98.4 SWR 3 D Hornisgrinde 80 927 SR3 jingle (not SWR) 30dBf
1936 96.2 SWR 2 D Hornisgrinde 80 927 D3A2 29dBf
1951 101.5 SRF 1 SUI Säntis 60 952 //web Mrs. Robinson song
1955 106.5 Antenne Vorarlberg AUT Bregenz/Pfänder 50 908 jingle ID [1st]
1956 89.6 Hitradio Ö3 AUT Bregenz/Pfänder 50 908 weak //99.0 [1st]
1958 102.1 FM 4 AUT Bregenz/Pfänder 50 908 20dBf //104.6 [1st]
2007 106.9 B5 aktuell D Grünten (Allgäu) 100 876 mono ~19dBf
2008 95.8 Bayern 3 D Grünten (Allgäu) 100 876 //98.5
2019 96.6 SRF 2 Kultur SUI Rigi/Kulm 30 1015 //web ~14dBf [1st]
2043 99.0 Hitradio Ö3 AUT Salzburg/Gaisberg 100 712 A203 36dBf
2045 94.8 Ö2 – R. Salzburg AUT Salzburg/Gaisberg 100 712 A802 Radio_S_30dBf

It was definitely some kind of a very highly elevated tropospheric duct. Both F5LEN’s and William Hepburn’s forecasts did not predict any extended propagation conditions between Switzerland and central Poland.

nwe006 nwe009 06 09

The high pressure system that developed such extraordinary tropo can be seen on the following maps:

pr1   pr2

2 thoughts on “December 2015: elevated SUI ducting

  1. Hi, I wonder what aerial and receiver you are using?
    ALos what is the “normal” range you have on FM when the band is flat (without tropo etc)
    Also have you tried 65-73mhz DXing? I’ve played about with a dipole and could pick up Kaliningrad here in Warsaw early in the morning in my flat on 10th floor, while when my dipole was on the roof, I was able to hear Kalinning rad non stop


    1. Hi Richard,

      I’m using modified XDR-F1HD tuner with two aerials:
      Körner 19.3 (H)
      2x Yagi 9-el K6STI (V)

      Well, the furthest location that I can receive with good stereo signal all the time is Przysucha/Kozłowiec at 147km. I can hear many stations up to around 300km with some fading without any tropo. Up to 700-900km distances are also possible daily via aircraft scatter mode (Serbia, Croatia, Bosnia).

      I have tried OIRT DXing, with a dedicated 9-el antenna and low noise preamp I was able to hear fair signal from Brest, Belarus every day with some slight fading at 291km.


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