|
Band name | abbr. | ITU band |
Frequency | Wavelength | Bands Allocated to Amateurs |
Extremely low frequency | ELF | 1 | 3 - 30 Hz | 10,000-100,000 km | none |
Super low frequency | SLF | 2 | 30 - 300 Hz | 1,000 - 10,000 km | none |
Ultra low frequency | ULF | 3 | 300 Hz - 3 kHz | 100 - 1000 km | none |
Very low frequency | VLF | 4 | 3 - 30 kHz | 10 - 100 km | none |
Low frequency Longwave (LW)* |
LF | 5 | 30 - 300 kHz | 1 - 10 km | **2200 m |
Medium frequency Medium-wave (MW)* |
MF | 6 | 300 - 3000 kHz | 100 - 1000 m | **630, 160 m |
High frequency Short-wave (SW)* |
HF | 7 | 3 - 30 MHz | 10 - 100 m | 80, 60, 40, 30, 20, 17, 15, 12, 10 m |
Very high frequency | VHF | 8 | 30 - 300 MHz | 1 - 10 m | **6, 4, 2, 1.25 m |
Ultra high frequency | UHF | 9 | 300 - 3000 MHz | 10 - 100 cm | **70, 23, 13 cm |
Super high frequency | SHF | 10 | 3 - 30 GHz | 1 - 10 cm | **5, 3, 1.2 cm |
Extremely high frequency | EHF | 11 | 30 - 300 GHz | 1 - 10 mm | **6, 4, 1 mm |
*Historical term used in the first half of the 20th century.
**Amateur radio frequency allocations vary around the world. Several bands are common for amateurs worldwide, usually in the HF part of the spectrum. Other bands are national or regional allocations only due to differing allocations for other services, especially in the LF, MF, VHF, and UHF parts of the radio spectrum.
The discovery and understanding of radio waves have a rich history. In the late 19th century, James Clerk Maxwell's equations provided the theoretical foundation for EM waves. It was Heinrich Hertz who first demonstrated the existence of radio waves in the laboratory in the 1880s. Hertz's experiments showed that electric sparks could produce and detect radio waves, marking a significant breakthrough.
However, it was Guglielmo Marconi who made practical use of radio waves for wireless communication in the early 20th century. His work led to the development of the first radio transmitters and receivers, paving the way for modern wireless communication systems.
Since the Big Bang Radio waves have been produced by various natural sources. One of the most prominent natural sources of radio waves is celestial objects, including stars, planets, and galaxies. Radio telescopes are specialized instruments designed to observe these cosmic radio emissions, allowing scientists to study the universe's hidden secrets. Earth's atmosphere also emits radio waves through processes like lightning strikes, which generate radio signals known as sferics (sometimes also spelled "spheric"). These natural radio emissions can be harnessed for meteorological and atmospheric studies.
Radio waves have an extensive range of practical applications in our daily lives. Some key uses include:
In conclusion, radio waves are a fundamental part of the EM spectrum with unique properties that make them indispensable for a wide range of human endeavors, from communication to scientific exploration and beyond. Their discovery and application have revolutionized how we connect, communicate, and explore the universe, making them an essential part of our daily lives and scientific endeavors.