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A Systematic Study of 7 MHz Greyline Propagation Using Amateur Radio Beacon Signals

Centre for Space, Atmospheric and Oceanic Science, University of Bath, Bath BA2 7AY, UK
Radio Systems, Faculty of EEMCS, University of Twente, 7522 NB Enschede, The Netherlands
Applied Physics Laboratory, The Johns Hopkins University, Laurel, MD 20723, USA
Liles Innovations LLC, Reston, VA 20191, USA
Autonomous Analytics, Southampton SO16 7PE, UK
Author to whom correspondence should be addressed.
Academic Editors: Emilia Correia, Jean-Pierre Raulin, Paulo Roberto Fagundes and José-Valentin Bageston
Atmosphere 2022, 13(8), 1340;
Received: 20 July 2022 / Revised: 15 August 2022 / Accepted: 17 August 2022 / Published: 22 August 2022
(This article belongs to the Special Issue Recent Advances in Ionosphere Observation and Investigation)
This paper investigates 7 MHz ionospheric radio wave propagation between pairs of distant countries that simultaneously lie on the terminator. This is known as greyline propagation. Observations of amateur radio beacon transmitters recorded in the Weak Signal Propagation Reporter (WSPR) database are used to investigate the times of day that beacon signals were observed during the year 2017. The WSPR beacon network consists of thousands of automated beacon transmitters and observers distributed over the globe. The WSPR database is a very useful resource for radio science as it offers the date and time at which a propagation path was available between two radio stations, as well as their precise locations. This paper provides the first systematic study of grey-line propagation between New Zealand/Eastern Australia and UK/Europe. The study shows that communications were predominantly made from the United Kingdom (UK) to New Zealand at around both sunset and sunrise times, whereas from New Zealand to the UK, communication links occurred mainly during UK sunrise hours. The lack of observations at the UK sunset time was particularly evident during the UK summer. The same pattern was found in the observations of propagation from Eastern Australia to UK, and from New Zealand and Eastern Australia to Italy and the surrounding regions in Europe. The observed asymmetry in reception pattern could possibly be due to the increase in electromagnetic noise across Europe in the summer afternoon/evening from thunderstorms. View Full-Text
Keywords: ionosphere; radio propagation; HF communications ionosphere; radio propagation; HF communications
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MDPI and ACS Style

Lo, S.; Rankov, N.; Mitchell, C.; Witvliet, B.A.; Jayawardena, T.P.; Bust, G.; Liles, W.; Griffiths, G. A Systematic Study of 7 MHz Greyline Propagation Using Amateur Radio Beacon Signals. Atmosphere 2022, 13, 1340.

AMA Style

Lo S, Rankov N, Mitchell C, Witvliet BA, Jayawardena TP, Bust G, Liles W, Griffiths G. A Systematic Study of 7 MHz Greyline Propagation Using Amateur Radio Beacon Signals. Atmosphere. 2022; 13(8):1340.

Chicago/Turabian Style

Lo, Sam, Nikola Rankov, Cathryn Mitchell, Benjamin Axel Witvliet, Talini Pinto Jayawardena, Gary Bust, William Liles, and Gwyn Griffiths. 2022. "A Systematic Study of 7 MHz Greyline Propagation Using Amateur Radio Beacon Signals" Atmosphere 13, no. 8: 1340.

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