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  2. Radio spectrum - Wikipedia

    en.wikipedia.org/wiki/Radio_spectrum

    The radio spectrum is the part of the electromagnetic spectrum with frequencies from 3 Hz to 3,000 GHz (3 THz ). Electromagnetic waves in this frequency range, called radio waves, are widely used in modern technology, particularly in telecommunication. To prevent interference between different users, the generation and transmission of radio ...

  3. Band diagram - Wikipedia

    en.wikipedia.org/wiki/Band_diagram

    At the junction of two different semiconductors there is a sharp shift in band energies from one material to the other; the band alignment at the junction (e.g., the difference in conduction band energies) is fixed. At the junction of a semiconductor and metal, the bands of the semiconductor are pinned to the metal's Fermi level.

  4. Electromagnetic spectrum - Wikipedia

    en.wikipedia.org/wiki/Electromagnetic_spectrum

    The electromagnetic spectrum is the full range of electromagnetic radiation, organized by frequency or wavelength. The spectrum is divided into separate bands, with different names for the electromagnetic waves within each band. From low to high frequency these are: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and ...

  5. 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 ...

  6. List of countries by system of government - Wikipedia

    en.wikipedia.org/wiki/List_of_countries_by...

    List of countries by system of government. World's states coloured by systems of government: Parliamentary systems: Head of government is elected or nominated by and accountable to the legislature. Constitutional monarchy with a ceremonial monarch. Parliamentary republic with a ceremonial president.

  7. Super high frequency - Wikipedia

    en.wikipedia.org/wiki/Super_high_frequency

    Radio bands. Super high frequency ( SHF) is the ITU designation for radio frequencies (RF) in the range between 3 and 30 gigahertz (GHz). This band of frequencies is also known as the centimetre band or centimetre wave as the wavelengths range from one to ten centimetres. These frequencies fall within the microwave band, so radio waves with ...

  8. 5G NR frequency bands - Wikipedia

    en.wikipedia.org/wiki/5G_NR_frequency_bands

    Frequency bands for 5G New Radio (5G NR), which is the air interface or radio access technology of the 5G mobile networks, are separated into two different frequency ranges. First there is Frequency Range 1 (FR1), [1] which includes sub-6 GHz frequency bands, some of which are traditionally used by previous standards, but has been extended to ...

  9. Very high frequency - Wikipedia

    en.wikipedia.org/wiki/Very_high_frequency

    VI. v. t. e. Very high frequency ( VHF) is the ITU designation [1] for the range of radio frequency electromagnetic waves ( radio waves) from 30 to 300 megahertz (MHz), with corresponding wavelengths of ten meters to one meter. Frequencies immediately below VHF are denoted high frequency (HF), and the next higher frequencies are known as ultra ...