Cycles for radio amateurs

The various cycles are of great importance to radio amateurs, as they have a significant influence on radio conditions. The most important aspects are summarised below:

 

Daily cycle:

  • Day and night cycle: During the day, the ionosphere is more ionised due to solar radiation, creating better conditions for high-frequency (HF) links. At night, the ionisation decreases, changing the radio conditions.
  • Brightness cycle: The strong ionising effect of the sun during the day facilitates the reflection of higher frequency radio waves. At night the ionisation decreases and the conditions change.
  • Twilight effects: Radio conditions change during twilight, causing special propagation effects.
  • Solar wind and geomagnetic disturbances: These can change daily and affect radio links.
  • Frequency dependence: Shortwave propagation conditions change throughout the day, while VHF radio links vary due to atmospheric conditions.

 

Annual cycle:

  • Seasons and ionosphere: In summer, the ionosphere is more ionised, creating better conditions for higher frequencies. In winter the ionisation is weaker.
  • Solar activity and seasons: The height of the sun varies with the seasons, affecting radio conditions.
  • Twilight and night-time behaviour: Transitions between day and night can create interesting effects such as fading or changes in range.
  • Weather and climate conditions: These can affect the propagation conditions for VHF radio links.
  • Sun position and propagation windows: The optimum times for certain frequencies change with the seasons.

 

11-year cycle (solar cycle):

  • Solar activity and sunspots: During solar maximum there are more sunspots and higher solar activity, leading to better shortwave radio conditions. Conditions are poorer during solar minimum.
  • Influence on the ionosphere: High solar activity leads to better reflective properties and allows greater distances. Low activity makes radio communication more difficult.
  • Solar and geomagnetic storms: These are more frequent during the maximum and can significantly disrupt radio communications.
  • Long-term planning and adaptation: Radio amateurs adapt their operating strategies to the solar cycle to achieve optimal connections.

 

To summarise: The daily, annual and 11-year cycles affect radio conditions through changes in the ionosphere and solar activity. Radio amateurs use this knowledge to optimise their activities and overcome challenges.