why require day and night for HF communication
Answers
Because HF radio waves depend upon the ionosphere for reflection, their propagation is affected by changes in the ionosphere. A good rule of thumb for the time of day is that the higher frequencies are best during daylight ( 10 to 29.9999 MHz) and lower frequencies work best at night ( 2 to 10 Mhz).
Answer:
Because HF radio waves depend upon the ionosphere for reflection, their propagation is affected by changes in the ionosphere. ... A good rule of thumb for the time of day is that the higher frequencies are best during daylight (10 to 29.9999 MHz) and lower frequencies work best at night (2 to 10 Mhz).
Explanation:
There is much about HF to be confused about. It is a High Frequency (HF), for example, which turns out to be lower than most of the frequencies we deal with on a daily basis. Younger pilots often hear from the older pilots about just how difficult it was to make a position report "back in the day," but it seems rather easy these days. It is true that technology has made the radios easier to use and the transmitted signals much clearer. But there are still a few things to be gained from learning the technical stuff behind the technology.
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