Search results
Results from the WOW.Com Content Network
The electromagnetic waves in each of these bands have different characteristics, such as how they are produced, how they interact with matter, and their practical applications. Radio waves, at the low-frequency end of the spectrum, have the lowest photon energy and the longest wavelengths—thousands of kilometers, or more.
The term "surface plasmon polariton" explains that the wave involves both charge motion in the metal ("surface plasmon") and electromagnetic waves in the air or dielectric ("polariton"). [ 1 ] They are a type of surface wave , guided along the interface in much the same way that light can be guided by an optical fiber.
Spectral intensity of sunlight (average at top of atmosphere) and thermal radiation emitted by Earth's surface. Shortwave radiation (SW) is thermal radiation in the optical spectrum, including visible (VIS), near-ultraviolet (UV), and near-infrared (NIR) spectra.
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 ...
The broadcast medium wave band now extends above the 200 m / 1,500 kHz limit. Early long-distance radio telegraphy used long waves, below 300 kilohertz (kHz) / above 1000 m. The drawbacks to this system included a very limited spectrum available for long-distance communication, and the very expensive transmitters , receivers and gigantic antennas.
A less ambitious idea of “broadband antenna” (often called “wideband”) is an antenna that continuously covers the proportionally widest amateur band, that spans 3.5–4.0 MHz (a 14% bandwidth), [b] without requiring an antenna tuner. There are many such designs, but those are not discussed here.
The waves are stable, and can travel over very large distances (normal waves would tend to either flatten out, or steepen and topple over) The speed depends on the size of the wave, and its width on the depth of water. Unlike normal waves they will never merge – so a small wave is overtaken by a large one, rather than the two combining.
In physics, magnetosonic waves, also known as magnetoacoustic waves, are low-frequency compressive waves driven by mutual interaction between an electrically conducting fluid and a magnetic field. They are associated with compression and rarefaction of both the fluid and the magnetic field, as well as with an effective tension that acts to ...