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

This paper investigates 7 MHz ionospheric radio wave propagation between pairs of distant countries that simultaneously lie on the terminator. is known as greyline propagation. Observations amateur beacon transmitters recorded in Weak Signal Propagation Reporter (WSPR) database are used to investigate times day signals were observed during year 2017. The WSPR network consists thousands automated and observers distributed over globe. a very useful resource for science it offers date time at which path was available two stations, well their precise locations. provides first systematic study grey-line New Zealand/Eastern Australia UK/Europe. shows communications predominantly made from United Kingdom (UK) Zealand around both sunset sunrise times, whereas UK, communication links occurred mainly UK hours. lack observations particularly evident summer. same pattern found Eastern Italy surrounding regions Europe. asymmetry reception could possibly be due increase electromagnetic noise across Europe summer afternoon/evening thunderstorms.