High Frequency (HF) radio units utilize radio frequencies between 3 and 30 MHz, which means the wavelengths are quite long (10 to 100 meters) and are readily refracted by the ionosphere (the upper most part of the atmosphere). This means that we can use the HF radio for medium- to long-range communications. In the upper (western) parts of the valleys, where the main camps are located, HF radios are the main method of communication with Scott Base—when it works. Because the transmission of HF radio waves is affected by the conditions of the ionosphere, weather conditions and solar activity play major roles in determining whether HF radios work at all in the Dry Valleys. When HF radios don’t work, then it’s time to bring out the Iridium phones.
Field Communications equipment. The Blue HF Radio is set up inside the green box, with an HF radio being charged and an Iridium satellite phone (with the yellow antenna).