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Shortwave bands are frequency allocations for use within the shortwave radio spectrum (the upper medium frequency [MF] band and all of the high frequency [HF] band). Radio waves in these frequency ranges can be used for very long distance (transcontinental) communication because they can reflect off layers of charged particles in the ionosphere and return to Earth beyond the horizon, a ...
Diathermy is produced by two techniques: short-wave radio frequencies in the range 1–100 MHz (shortwave diathermy) or microwaves typically in the 915 MHz or 2.45 GHz bands (microwave diathermy), the methods differing mainly in their penetration capability. [4] [5] [6] It exerts physical effects and elicits a spectrum of physiological responses.
These were limited to frequencies of 0.1 – 2 MHz, called "longwave" diathermy. The current was applied directly to the body with contact electrodes, which could cause skin burns. In the 1920s the development of vacuum tube machines allowed frequencies to be increased to 10 – 300 MHz, called "shortwave" diathermy. The energy was applied to ...
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 ...
Shortwave radio is radio transmission using radio frequencies in the shortwave bands (SW). There is no official definition of the band range, but it always includes all of the high frequency band (HF), which extends from 3 to 30 MHz (100 (exactly 99.930819333) to 10 (exactly 9.9930819333) meters); above the medium frequency band (MF), to the ...
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 ...
The FCC limits for maximum permissible workplace exposure to shortwave radio frequency energy in the range of 3–30 MHz has a plane-wave equivalent power density of (900/ f 2) mW/cm 2 where f is the frequency in MHz, and 100 mW/cm 2 from 0.3 to 3.0 MHz.
Shortwave listening. Shortwave listening, or SWLing, is the hobby of listening to shortwave radio broadcasts located on frequencies between 1700 kHz and 30 MHz (30 000 kHz).[1] Listeners range from casual users seeking international news and entertainment programming, to hobbyists immersed in the technical aspects of long-distance radio ...