HFThe HF band has been the traditional space for amateur operators since the start of radio broadcasts. The HF frequency range spans from 150kHz up to 30MHz and is divided into several bands (160m, 80m, 40m, 20m, 10m, and others) for amateur use. Using HF bands often requires a full license. In some countries novice licenses are also allowed to use (parts of) HF frequencies.
The physical properties of the HF radio waves allows for great distances to be covered, spanning the entire globe. Atmospheric conditions, weather, temperature and other factors determine how well HF waves can travel the ether. For this reason bands can open and close depending on season and time of day.
HF-rigsA general coverage rig usually covers all bands between 160 and 10m. Many modern HF rigs also incorporate the 6m band. Typical power output is 100W SSB, some high end rigs put out 200W. QRP (low power) rigs will only do 5 or 10W.
On the bands below 10MHz LSB (lower side band) modulation is generally used for phone communications. Above 10MHz, USB is used. This is a gentleman's agreement, so stations can (and will) use other types of modulation from time to time.
HF-antennasGood HF antennas are large by definition. A widely used design is the 1/2 wave dipole. For the 160m band, this antenna must have an optimal length of about 2x 40m. Several design tricks are used to get away with shorter antennas, sometimes with surprisingly good results, mostly not so good.
is by using a good antenna