WordNet
n. 30 to 300 gigahertz [syn: EHF]
Wikipedia
Extremely high frequency (EHF) is the ITU designation for the band of radio frequencies in the electromagnetic spectrum from 30 to 300 gigahertz. It lays between the Super high frequency band, and the Far infrared band which is also referred to as the terahertz gap. Radio waves in this band have wavelengths from ten to one millimetre, giving it the name millimetre band or millimetre wave, sometimes abbreviated MMW or mmW. Millimetre length electromagnetic waves were first investigated in the 1890s by pioneering Indian scientist Jagadish Chandra Bose.
Compared to lower bands, radio waves in this band have high atmospheric attenuation; they are absorbed by the gases in the atmosphere. Therefore, they have a short range and can only be used for terrestrial communication over about a kilometer. In particular, signals in the 57–64 GHz region are subject to a resonance of the O molecule and are severely attenuated. Even over relatively short distances, rain fade is a serious problem, caused when absorption by rain reduces signal strength. In climates other than deserts absorption due to humidity also affects propagation. While this absorption limits potential communications range, it also allows for smaller frequency reuse distances than lower frequencies. The short wavelength allows modest size antennas to have a small beam width, further increasing frequency reuse potential.
Usage examples of "extremely high frequency".
That device will broadcast a multi-channel EHF - that's extremely high frequency - signal out of the aircraft.
Being ultrasound at extremely high frequency, it is highly directional.
These, apparently, were generating current at an extremely high frequency.
Eventually the men were subjected to magnetic fields of extremely high frequency.
Now he was able to show that if the current was boosted to an even greater voltage then it became of extremely high frequency, and no cables at all would be required.
The transceivers in their radiation suits operated at an extremely high frequency and though it would be a minor miracle if the Sallon monitors happened to pick up their conversations, such a possibility had to be reckoned with.