High Frequency, between 10 and 30MHz is actually one of the lower frequency bands available to UK amateurs. Because of the long wavelengths at these frequencies, worldwide communications are easily achievable on HF.
The distances are dependent on the band conditions, what we refer to as propagation, and vary with the time of day and time of year as well as other factors. Our radio waves are reflected by the ionosphere and back to earth at great distances from our location, often this reflection happens more than once.
You don’t need high power levels either, with an efficient antenna in a good location, worldwide contacts can be made on very low power. Using Morse or some of the newer computer-generated data modes, this can open up the world of HF communication to even Foundation license holders.
Many contests take place on HF during the year, as well as special events such as IOTA, Islands On The Air, where contacts are made with as many islands as possible, Castles and Stately Homes On The Air, Mills On The Air, Railways On The Air and the annual Scouts and Guides event – Jamboree On The Air.