shortwaveband

Shortwave band refers to the portion of the radio spectrum broadly defined as shortwave, comprising approximately 3 to 30 megahertz (MHz). It is part of the high-frequency (HF) band and is used for long-distance radio communication because these frequencies can reflect off the ionosphere, allowing signals to travel beyond the line of sight.

Propagation is driven by ionospheric reflection (skywave), which varies with solar activity and time of day. During daylight, the D-layer can absorb lower frequencies, limiting long-range paths; at night, the higher F-region reflects signals more effectively, enabling farther reception. Propagation is also affected by the solar cycle, atmospheric noise, and solar flares, which can cause rapid changes.

Uses include international broadcasting, amateur radio, maritime and aviation communications, and government or military transmissions. Shortwave remains a means for listeners to receive stations from distant regions, but reception quality depends on time, location, interference, and atmospheric conditions.

Reception and equipment: The shortwave band is accessed with a variety of receivers and antennas, such as long-wire or beverage antennas. Transmitters are operated by international broadcasters and other services. Modern reception includes digital modes in addition to traditional narrowband analog. Frequency allocations within the shortwave spectrum are defined by international and national regulators and may vary by country.