Amateur Radio Propagation Studies

Science, research, engineering, operating

This page provides a brief overview on the most important results and findings communicated on this web site. All this achievements were made possible by the many fellow radio amateurs having contributed observation data, thoughts and ideas and other types of contributions. There are indeed many open questions when dealing with radio propagation phenomena because professional science hasn't yet solved all the puzzles. Thus, radio amateurs may still find many effects and phenomena worth to be examined in detail. However, some of the puzzles were already solved here ....

In August 2005, radio amateurs have managed extraordinary 144 MHz dx QSOs from England/Ireland into the eastern Atlantic which landmarked new tropo records in the IARU region 1.

A detailed analysis documents the meteorological origin of this dx events by identifying intense tropospheric inversion layers along the 3.700 km radio path.

Tropospheric dx QSOs exceeding the distance of 3.000 kilometers must be considered a true rarity in amateur radio.

By referring to various ham radio resources, a list of almost 100 examples of very long distance tropo QSOs and beacon observations is obtained (3.000 to more than 6.000 km, 144 MHz to 5.78 GHz) which reveals a number of systematical features. It is shown that all this dx QSOs may be interpreted by the meteorological conditions within the subtropical calms which has finally motivated the term Hadley cell propagation.

On May 20, 2003 radio amateurs from the Canary Islands reported many 144 MHz QSOs to central Europe and England corresponding to radio path lengths of 3.000 to more than 3.500 kilometers. Does this dx event represent double hop sporadic E or did tropospheric dx propagation extend the radius of single hop sporadic E?

In a Sherlock Holmes type of analysis, Udo (DK5YA) and Volker (DF5AI) discuss a variety of possible propagation modes by analysing dx reports from radio amateurs, vertical profiles of meteorological data, ionograms and other material. A stricing feature was found in the analysis, i.e. in sixty percent of all dx QSOs lakes and major rivers were found at the radio path center. We have therefore speculated about double hop sporadic E propagation enabled by radio glint in lakes and rivers and, as an alternative, we have also speculated about radiowaves reflected at the topside of tropospheric inversion layers correlating with the geographical position of rivers and lakes.

Assuming the above model of radio glint in lakes and rivers (or, alternatively, the model of radiowave reflection at the topside of tropospheric inversion layers) is indeed justified, the results may be extrapolated to other regions in Europe as well, e.g. to the lake Balaton in Hungary.

A number of dx target maps have been created describing the indivdiual role of major lakes in sporadic E double hop propagation leading to a surprising result: a couple of 'historical' examples of very long distance QSOs in 144 MHz may be now explained quite accurately, e.g. the 144 MHz QSO between the souther tip of Norway and the island of Crete as well as dx QSOs between northern Germany and the Caspian Sea.

In 2006, the number of 144 MHz double hop sporadic E QSOs has increased considerably providing new opportunities of continuing the analyses started in 2003 (see above).

By using satellite and aerial images of the Google Earth internet service, all double hop sporadic E QSOs in 2006 indicate a striking correlation between the position of the QSOs' geographical center and the position of big lakes and major rivers. It is therefore concluded that the above speculations were indeed justified, i.e. sporadic E double hop propagation is strongly correlated to major rivers and lakes located at the radio path center.

This web site addresses even 'hot potatoes' in the world of VHF radio propagation, e.g. the speculation of thunderstorms triggering sporadic E forward scatter on very high frequencies.

An international team of radio amateurs (Sabine, DL1DBC, Allard, PE1NWL, Udo, DK5YA, Gabriel, EA6VQ, Joachim, DL8HCZ and Volker, DF5AI) has addressed this subject and concludes: thunderstorm effects on 144 MHz sporadic E cannot be principally excluded. Considering the afternoon of June 27, 2004 they have found a long geographical band of sporadic E activity which appears to correlate to a very similar band of thunderstorm activity.

For more than 30 years, radio amateurs observe Aurora dx QSOs violating the geometrical model of field-aligned backscatter considerably.

Having analysed the frequent dx QSOs between Oliver (DL1EJA) and Peter (SM2CEW), the nature of this 'unusual' Aurora QSOs was finally solved: the so-called aspect angle may deviate from 90 degree by some degree which may result in unusual dx QSOs.

Meanwhile, many examples of unusual Aurora QSOs have been analysed from this perspective and all this QSOs may be explained quite accurately. In the dx QSO between DK3UZ (northern Germany) and UA1ZCL (Murmansk), the aspect angle deviates from perpendicularity by 20 degree corresponding to the largest ever observed deviation from 'ordinary Auroral backscatter' in ham radio I am aware of.

Radio and visual observation of northern lights follow different rules. You may view visual Aurora Borealis anywhere in the sky but you cannot receive radio signals from Auroral backscatter in all antenna directions.

For the first time, the actual dx range in Aurora dx communication has been calculated in detail by considering radio stations in various geographical regions of Europe and North America.

On March 28, 2001, a coronal mass ejection (CME) near the active sunspot region 9393 hurled a high-speed solar wind stream of electrified, magnetic gas towards the Earth. On March 31, 0053 UT, this shock front pushed into the dayside magnetosphere causing geomagnetic field disturbances and other types of phenomena including wide spread Aurora band openings on very high frequencies.

By addressing the world-wide community of VHF radio amateurs, the author has obtained information on more than 3.800 Aurora QSOs from Europe, North America and Australia which are all associated with this geomagnetic storm event. The POES team at NASA has supported the study by contributing a full overview on the Auroral activity in the northern and southern hemisphere on this particular day. For the very first time, the spatiotemporal development of Aurora dx communication has been analysed from a global perspective. The analysis revealed a wealth of information, e.g. the correlation between Aurora dx activity and the actual direction of the interplanetary magnetic field, unusual maxima in the distribution of QSO distances, animations which demonstrate, for example, the variation of Auroral and QSO activity during the day and many more details.

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