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  2. High frequency - Wikipedia

    en.wikipedia.org/wiki/High_frequency

    HF's position in the electromagnetic spectrum.. High frequency (HF) is the ITU designation [1] for the band of radio waves with frequency between 3 and 30 megahertz (MHz). It is also known as the decameter band or decameter wave as its wavelengths range from one to ten decameters (ten to one hundred meters).

  3. Low-velocity zone - Wikipedia

    en.wikipedia.org/wiki/Low-velocity_zone

    The existence of the low-velocity zone was first proposed from the observation of slower than expected seismic wave arrivals from earthquakes in 1959 by Beno Gutenberg. [6] He noted that between 1° and 15° from the epicenter the longitudinal arrivals showed an exponential decrease in amplitude after which they showed a sudden large increase.

  4. Electromagnetic spectrum - Wikipedia

    en.wikipedia.org/wiki/Electromagnetic_spectrum

    Ultra high frequency: 1 m: 300 MHz: 1.24 μeV Radio waves: VHF Very high frequency: 10 m 30 MHz 124 neV: HF High frequency: 100 m 3 MHz 12.4 neV MF Medium frequency: 1 km: 300 kHz: 1.24 neV LF Low frequency: 10 km 30 kHz 124 peV: VLF Very low frequency: 100 km 3 kHz 12.4 peV ULF Ultra low frequency: 1 Mm: 300 Hz: 1.24 peV SLF Super low ...

  5. Radio spectrum - Wikipedia

    en.wikipedia.org/wiki/Radio_spectrum

    High frequency [18] VHF: 0.03 to 0.3 GHz: Very high frequency [18] UHF: 0.3 to 1 GHz: Ultra-high frequency [18] L: 1 to 2 GHz: Long wave S: 2 to 4 GHz: Short wave C: 4 to 8 GHz: Compromise between S and X X: 8 to 12 GHz: Used in World War II for fire control, X for cross (as in crosshair). Exotic. [19] K u: 12 to 18 GHz: Kurz-under K: 18 to 27 ...

  6. Extremely low frequency - Wikipedia

    en.wikipedia.org/wiki/Extremely_low_frequency

    Extremely low frequency (ELF) is the ITU designation [1] for electromagnetic radiation (radio waves) with frequencies from 3 to 30 Hz, and corresponding wavelengths of 100,000 to 10,000 kilometers, respectively. [2] [3] In atmospheric science, an alternative definition is usually given, from 3 Hz to 3 kHz.

  7. Equatorial wave - Wikipedia

    en.wikipedia.org/wiki/Equatorial_wave

    The remaining pair of roots correspond to the Yanai or mixed Rossby-gravity mode whose group velocity is always to the east [1] and interpolates between two types of > modes: the higher frequency Poincaré gravity waves whose group velocity can be to the east or to the west, and the low-frequency equatorial Rossby waves whose dispersion ...

  8. Radio propagation - Wikipedia

    en.wikipedia.org/wiki/Radio_propagation

    Radio propagation is the behavior of radio waves as they travel, or are propagated, from one point to another in vacuum, or into various parts of the atmosphere. [1]: 26‑1 As a form of electromagnetic radiation, like light waves, radio waves are affected by the phenomena of reflection, refraction, diffraction, absorption, polarization, and scattering. [2]

  9. Ultra low frequency - Wikipedia

    en.wikipedia.org/wiki/Ultra_low_frequency

    Ultra low frequency (ULF) is the ITU designation [1] for the frequency range of electromagnetic waves between 300 hertz and 3 kilohertz, corresponding to wavelengths between 1,000 to 100 km. In magnetosphere science and seismology , alternative definitions are usually given, including ranges from 1 mHz to 100 Hz, [ 2 ] 1 mHz to 1 Hz, [ 3 ] and ...