Solar cycle 24 began on January 4, 2008 and so far has been the smallest sunspot cycle since 1904. Solar cycle 24 “is on track to be the Solar Cycle with the lowest recorded sunspot activity since accurate records began in 1750.”
Solar cycles supposedly have a duration of about 11 years.
“In radio communication, skywave or skip refers to the propagation of radio waves reflected or refracted back toward Earth from the ionosphere, an electrically charged layer of the upper atmosphere. Since it is not limited by the curvature of the Earth, skywave propagation can be used to communicate beyond the horizon, at intercontinental distances. It is mostly used in the shortwave frequency bands.”
Most long-distance HF radio communication—between 3 and 30 MHz—is a result of skywave propagation.
“Since the early 1920s amateur radio operators (or “hams”), limited to lower transmitter power than broadcast stations, have taken advantage of skywave for long distance (or “DX”) communication.”
