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HF's position in the electromagnetic spectrum.. High frequency (HF) is the ITU designation [1] [2] 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).
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 gamma rays. The electromagnetic waves in each of these bands have different characteristics, such as how they are ...
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 ...
Atmospheric waves, associated with a small dust storm of north western Africa on 23 September 2011. An atmospheric wave is a periodic disturbance in the fields of atmospheric variables (like surface pressure or geopotential height, temperature, or wind velocity) which may either propagate (traveling wave) or be stationary (standing wave).
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.
Namely, the mean sea level oscillates with a wavelength that is equal to the length of the group, with a low level where the wind waves are highest and a high level where these waves are lowest. This oscillation of the sea surface is proportional to the square of the short wave amplitude and becomes very large when the group speed approaches ...
Medical applications of radio frequency (RF) energy, in the form of electromagnetic waves (radio waves) or electrical currents, have existed for over 125 years, [9] and now include diathermy, hyperthermy treatment of cancer, electrosurgery scalpels used to cut and cauterize in operations, and radiofrequency ablation. [10]
As losses increase with frequency, high frequency transmissions between 3 and 30 MHz have more modest groundwave range and groundwave is unimportant above 30 MHz. [1] Surface conductivity affects the propagation of ground waves, with highly conductive surfaces such as sea water providing the best propagation, and dry ground and ice performing ...