Out of the four seasons, autumn is well known among radio enthusiasts as the best period for spectacular propagation of radio waves. The tropospheric ducting is a propagation mode based on temperature inversion in the vicinity of the Earth’s surface. Such an enhancement extends the regular line-of-sight distribution of electromagnetic waves to the areas out of their general, daily service. During special conditions, air layers may form some kind of a guide for the radio signals. This phenomenon usually happens during periods of stable anticyclonic weather and affects radio frequencies in VHF, UHF and microwave bands. While it is possible to watch distant TV channel or listen to a foreign FM station, one can also check other, less explored radio frequencies… like the 5 GHz band widely used for the wireless LAN communication.
Antenna and rotator installed on a 18 meter mast (read more: Ubiquiti RocketDish 5G31-AC)
My location is near Płock in central Poland. The dual-polarization 5 GHz parabolic dish antenna with gain rated at 31 dBi is installed on a 18 meter mast (+114 m ASL) together with a rotator. It can be controlled remotely from anywhere. My software and hardware allows a detailed network logging, as well as rotator controlling, which can work in special radar mode, rotating back and forth within a specified azimuth range.
This year was really extraordinary in Poland. The spring was very amazing, as both April and May smashed through all previous temperature records. We have also experienced the warmest summer, at least since the beginning of measurements in 1781. Such weather allowed often occurrence of radiation inversions that produced good tropospheric propagation throughout nights and mornings. I set my previous personal Wi-Fi DX reception record in May twice in a row from Wolin, Poland during unattended scanning on 2018-05-28 and 2018-05-29 mornings, at a distance of 370 km.
In the first half of October 2018, a high pressure system settled down over Eastern Europe and brought excellent propagation conditions in Poland. Again, the summer-like weather brought sunny days and 20-25 °C temperatures. This time I logged some networks from Ukraine, Lithuania and almost… 3600 other from Poland. Read more / Czytaj dalej →
A widespread high pressure system settled down over Europe in the middle of October 2017. It brought a summer-like weather to Poland with temperatures as high as 26°C measured in Wrocław. Excellent weather conditions, so called a Polish golden autumn, continued for several days. When the atmospheric pressure started to decrease again, the wind had also weakened. This provided favorable circumstances for temperature inversions and tropospheric ducting on VHF, UHF and microwave radio bands.
I have been observing propagation conditions within WLAN frequencies for many years. The 5 GHz band is very crowded in Poland, as it is widely used by the internet service providers with outdoor devices installed on tall buildings like chimneys, blocks of flats or lattice masts. In 2015 I detected some networks from Southern Poland and Czech Republic. I also fixed my personal reception record at 346.5 km. Since then I have started saving money for a taller mast, because the antenna (8 m AGL) was looking mostly at trees that greatly attenuate all microwave signals.
At the beginning of October I finally finished a new 18 meter mast with a parabolic dish for the 5 GHz band. Ubiquiti RocketDish 5G31-AC is a dual polarization 5.1-5.8 GHz antenna rated at 31 dBi. It is connected to MikroTik Routerboard RB912 radio behind the dish in a custom aluminium box. The mast is equipped with a rotator and everything can be remotely controlled. Read more / Czytaj dalej →
The forecasts suggested some upcoming long-range tropospheric ducting from Sweden, Norway and Finland in October. According to maps, as usually, the strongest tropo was expected over the Baltic Sea, with just marginal strength extending to my location. Nevertheless I was prepared to check the propagation conditions remotely.
Read more / Czytaj dalej →
This is the continuation of the article: August 2016: extreme VHF tropo (F, HRV, BIH, I) – part I.
August 26, 2016 was definitely a remarkable day for the European long-range tropospheric propagation. Zagreb was logged in Finland by several DX-ers, up to 1691 km, however in Poland the best conditions occurred one day later, on August 27th.
But first, let’s go back in time to the year 2014 when I wrote an article titled Autumn Tropo 2014 (D, HRV, SVN…), especially to the last paragraph:
Italy was very close this time, as the tropo ducting would have to cross only the Adriatic Sea. Unfortunately, all interesting frequencies were overtaken by closer stations here in Płock. The closest Italian locations are blocked by the Alps, but maybe someday we could receive it in Poland across Croatia and Adriatic Sea instead…?
The described path, across Adriatic Sea, was just a wishful thinking and actually I have never expected it to occur. Well, guess what happened… Read more / Czytaj dalej →
August 2016 started with a cold and rainy weather, which continued for more than half of the month. It had some advantages though, as the radio band was clear of tropo signals during peak of the Perseids. Thankfully, the end of August was much more exciting and brought a superior tropospheric ducting propagation conditions. It started with distant Germany, Denmark, Sweden, Austria, France and then, after three days, moved more into central Europe, to a completely unexpected set of countries: Slovenia, Croatia, Bosnia and Herzegovina and… ITALY!
Long range tropospheric ducting was lasting this time for 6 days – starting from August 23 until Sunday, August 28. Because of a very high amount of notable DX receptions, this article describes only the first three days of this awesome tropo opening. Read more / Czytaj dalej →
The weather in first days of summer brought a widespread high pressure system that has settled down over Eastern and Central Europe. Very good tropospheric conditions were forecasted between Germany, Switzerland, Czech Republic and partially Poland.
In the evening on June 23, I quickly checked the signals before sleep. There was nothing interesting on the 87.5-108 MHz band… except one low modulated station on 107.3. I have already received hr4 from Germany on this frequency twice before, but with weak signal levels. I was quite busy, so I kept the 107.3 tuned for any upcoming identification. In a moment I saw a PI code: D704. Well, that was odd, because I thought that hr4 carries a different PI code. And I was right, shortly I heard an ID – SWR4 verkehr! So, this time I got Raichberg @ 898 km on this frequency. Read more / Czytaj dalej →