The high-frequency band is the radio-frequency (RF) band the range
3-30 MHz. The HF band provides relatively reliable propagation over
long distances. Reasonable efficient antennas can be built requiring low
radiated power. Propagation is principally by sky wave and therefore
depends on the vagaries of the ionosphere with fading and
multi-path effects often limiting the speed of communication. Surface wave
communications over short distances (~50 km) are also possible. The
band is used for fixed services, mobile services, amateur transmissions,
broadcasting, and maritime mobile service. Until the advent of satellite
communications, the HF band provided the only means of long-distance
communication.
Other topics in our resources on Communications Systems related to HF include: