↑ What Are Radio Waves?

Edited by Doron Tal, 4X4XM
  1. Essence and basic nature

    2. Radio waves are a form of electromagnetic radiation generated by oscillating electric and magnetic fields, both perpendicular to the wave's propagation direction. They travel at the speed of light and can easily pass through different materials, including the Earth's atmosphere. With their ability to travel long distances and pass through various materials, radio waves continue to be an essential part of modern technology.

  2. Wavelength, frequencies and spectrum

    3. Radio waves (like waves on a pond) have series of repeating peaks and valleys of electric and magnetic fields.
    Their wavelengths range from less than a millimeter to over 100,000 kilometers (10-3 - 108 meter); frequencies 3 Hz - 300 GHz.

    Radio waves are classified based on their frequency and wavelength. Lower frequency waves have longer wavelengths, and higher frequency waves have shorter wavelengths. Different bands are used for specific purposes.

    Band name abbr. ITU
    band    		 Frequency Wavelength Amateur
    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 LF 5 30 - 300 kHz 1 - 10 km *2200 m
    Medium frequency MF 6 300 - 3000 kHz 100 - 1000 m *630, 160 m
    High frequency 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 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

    *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.

  3. Usage and applicaitons

    4. Radio waves are an important part of modern technology as they enable long-range communication, wireless information access, and exploration of the universe.
    They have a wide range of applications, from broadcasting AM radio, FM radio, and Wi-Fi, cellular and satellite communication. Additionally, they play a significant role in space exploration.

    References:
  1. Radio wave Wikipedia
  2. What are radio waves? NASA
  3. Radio Waves UCAR
  4. What are radio waves? Northwestern.edu
  5. Electromagnetic radiation Wikipedia
  6. Electromagnetic spectrum Wikipedia
  7. Radio spectrum Wikipedia
  8. Tour of the Electromagnetic Spectrum NASA