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The HF (High Frequency) bands — spanning from 1.8 MHz to 30 MHz — are where amateur radio becomes a truly global hobby. Through a phenomenon called ionospheric propagation, HF signals can bounce between the Earth's surface and layers of the ionosphere, travelling hundreds or thousands of kilometres with relatively modest equipment. A 100-watt transceiver and a wire antenna in the back garden can reach the other side of the world when conditions are right.
Amateur operators have access to several allocations within the HF spectrum. Each band has its own character, propagation behaviour, and typical uses. The exact frequency limits vary by country and licence class — check your national band plan for details.
Often called "Top Band," this is the lowest amateur HF allocation. Propagation is primarily via ground wave during the day and via the ionosphere at night. It is a challenging band that rewards patience and good antennas. Noise levels can be high, especially in urban environments. Most activity is on CW and SSB.
A popular band for regional and medium-distance communication, particularly in the evening and overnight hours. It is well suited for nets and ragchewing. The band can be noisy, especially in summer, due to atmospheric static (QRN). In ITU Region 2 (the Americas), amateurs have access to the full 3.5–4.0 MHz range, while allocations in other regions are narrower.
A relatively new amateur allocation in many countries, with limited channelized or narrow-band access. Regulations vary significantly — some countries permit only specific frequencies, while others allow a small continuous band. Power limits are typically lower than on other HF bands. The band offers useful propagation characteristics that fill the gap between 80 and 40 metres.
One of the most versatile HF bands. During the day, it provides reliable communication out to about 800 km (500 miles). At night, the band opens up for worldwide DX. It is popular for CW, SSB, digital modes, and nets. The 7.0–7.2 MHz segment is available to amateurs worldwide; 7.2–7.3 MHz is primarily available in ITU Region 2.
A narrow band (50 kHz wide) shared with non-amateur services on a secondary basis. It is restricted to CW and data/digital modes — no voice is permitted. Despite its narrow bandwidth, 30 metres offers excellent propagation and is popular for FT8, CW, and other low-bandwidth modes. Power is limited to 200 watts in many countries.
The premier DX band. Open for long-distance communication during daylight hours, and often for much longer during peak solar cycles. It is one of the most active and popular HF bands, with constant activity in CW, SSB, and digital modes. If you can only put up one HF antenna, 20 metres is often the recommended choice.
One of the "WARC bands" (named after the 1979 World Administrative Radio Conference that allocated them). It offers good DX potential, especially during moderate to high solar activity. The band is typically less crowded than 20 metres and provides an enjoyable alternative. No contest activity is permitted on the WARC bands.
An excellent DX band when solar activity is moderate to high. During solar minimum, 15 metres can seem dead for weeks, but during solar maximum it provides superb worldwide propagation. Activity includes CW, SSB, and digital modes.
Another WARC band. Like 15 metres, it is heavily influenced by the solar cycle. When open, it offers good DX with relatively low crowding. No contest activity is permitted.
The highest HF amateur band. During solar maximum, 10 metres provides outstanding worldwide DX with modest equipment — small antennas work well at this frequency. During solar minimum, the band may only support local communication via ground wave or sporadic-E propagation. The band is also home to FM repeaters (around 29.6 MHz) and satellite downlinks.
Successful HF operating depends on understanding how signals travel. The key concepts are:
Ionospheric skip — HF signals travel beyond the horizon by refracting off ionized layers in the upper atmosphere. The frequency at which this works depends on the time of day, season, solar activity, and the specific ionospheric conditions. Lower bands (80, 40 metres) tend to work better at night, while higher bands (20, 15, 10 metres) tend to work better during daylight.
Solar cycle — The Sun goes through approximately 11-year cycles of activity. During solar maximum, higher HF bands open up for worldwide communication. During solar minimum, activity on 10 and 15 metres drops significantly, and operators concentrate on the lower bands. See Propagation for more detail.
Skip zone — On HF, there is often a "dead zone" between the limit of ground wave propagation and where the sky wave first returns to earth. Stations in this zone cannot hear you, even if stations much further away can.
Grey line — The boundary between daylight and darkness on the Earth's surface provides enhanced propagation, particularly on the lower HF bands. Operators who time their activity to coincide with sunrise or sunset can often make unexpected contacts.
A basic HF station consists of an HF transceiver, an antenna, a power supply, and feedline. Modern HF transceivers typically cover all amateur bands from 160 to 10 metres and include built-in features like antenna tuners, DSP filtering, and digital mode interfaces. See Equipment Overview for guidance on choosing a radio.
HF antennas are larger than VHF/UHF antennas because the wavelengths are longer. Common starter antennas include random wire antennas with a tuner, end-fed half-wave antennas, and fan dipoles that cover multiple bands. Even a simple wire antenna can produce excellent results on HF. See Antennas Overview for options.
When operating on HF, keep these practices in mind:
The HF bands support a wide variety of operating activities:
When working a rare DX station, you will frequently encounter split operating. The DX station transmits on one frequency but listens on a different frequency (or range of frequencies). This prevents the pileup of calling stations from covering up the DX station's signal.
When you hear a station say "listening up" or "up 5," it means they are listening 5 kHz above their transmit frequency. Set your radio to transmit on the listening frequency while receiving on the DX station's frequency. Most modern transceivers have a split or VFO A/B function for this purpose.