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What are the ranges of radio spectrum?
From about 9 kilohertz (kHz) to thousands of gigahertz (GHz). This portion is referred to as the RF Spectrum. As the frequency is increased beyond the RF spectrum, electromagnetic energy takes the form of infrared (IR), visible light, ultraviolet (UV), X rays, and gamma rays. The ranges, or frequency bands, are as follows. 3kHz to 30kHz v.l.f. Very low frequency 30kHz to 300kHz l.f. Low 300kHz to 3MHz m.f. Medium 3MHz to 30MHz h.f. High 30 MHz to 300MHz v.h.f. Very high 300MHz to 3GHz u.h.f. Ultra-high 3GHz to 30GHz s.h.f. Super-high 30GHz to 300GHz e.h.f. Extra-high
What is microwave wireless communication?
Microwave wireless communication is a Line of Sight communication. Microwave communication occurs at 3Ghz to 30Ghz. Line of Sight means there should not be any restriction between the Antenna i.e. two antenna can see to each other. it is an easy way for communication. In telecom field,Microwave communication is used to Link BSC to BSC,BSC to MSC and MSC to MSC and so on.
Do wireless keyboards send data to the computer using microwave frequencies?
Whether a wireless computer keyboard uses microwave frequencies for communication with the computer depends on the technology used by the keyboard, and on the definition of microwave frequencies. Wikipedia defines microwave frequencies to be in the 1...30GHz range. Many wireless keyboards operate in the 2.4GHz band, which would make them microwave transmitters (and receivers). Other keyboards use different frequencies, below 1GHz. Those would not be microwave devices, according to this definition. The 802.15.4 standard, for example, lists a 868.0-868.6MHz band (Europe), 902..928MHz (US) and the 2.4GHz (2400...2483.5 MHz) band (worldwide, but subject to regional restrictions).
What are 3 forms of Electromagnetic Radiation with a wavelength greater than visible light?
Infrared is one, radio waves are another and many include microwaves as a third but microwaves are used for communications and are a form of radio wave. Wavelengths between radio waves and infrared are called TeraHertz radiation. Radio waves start at very long wavelengths LF or low frequency defined as 30kHz to 300kHz, MF or medium frequency from 300kHz to 3MHz, HF or high frequency from 3MHz to 30MHz, VHF or very high frequency from 30MHz to 300MHz, UHF or ultra high frequency from 300MHz to 3GHz and SHF from 3GHz to 30GHz. After that they are normally just called microwaves. Many microwave ovens operate near 2.4GHz which is only UHF.
Radio signals are broadcast by what waves?
Radio waves are electromagnetic waves. Electromagnetic waves include waves such as X rays, ultraviolet light, visible light, infrared rays and so on, but you probably imagine radio waves to be quite different from these waves. Of the various kinds of electromagnetic waves, radio waves have a longer wave length than infrared rays, and are defined by the Radio Law as 'electromagnetic waves with a frequency of less than 3,000 GHz (3 THz)'Ultralow frequency radio wavesbelow 3kHzradio waves3kHz~3THz infrared rays3THz~380THz visible light380THz~790THz ultraviolet light790THz~105THz X rays105THz~107THz γ raysabove 107THzNames of radio waves Frequency Wave length Principal applications VLF(Very Low Frequency) 3kHz ~ 30kHz 100km ~ 10km LF(Low Frequency) 30kHz ~ 300kHz 10km ~ 1km Vessel / Airplane beacon MF(Medium Frequency) 300kHz ~ 3MHz 1km ~ 100m AM radio, Marine radio, Amateur radio HF(High Frequency) 3MHz ~ 30MHz 100m ~ 10m Shortwave broadcasting, Marine / Air radio, Amateur radio VHF(Very High Frequency) 30MHz ~ 300MHz 10m ~ 1m TV, FM, Fire radio, Police radio, Disaster PA radio network UHF(Ultra High Frequency) 300MHz ~ 3GHz 1m ~ 10cm Low power radio, Mobile-phone, Taxi radio, Amateur radio, TV, Wireless LAN SHF(Super High Frequency) 3GHz ~ 30GHz 10cm ~ 1cm Satellite broadcasting, Radar EHF(Extremely High Frequency) 30GHz ~ 300GHz 1cm ~ 1mm Satellite broadcasting, Radio astronomy, Radar submillimeter waves 300GHz ~ 3THz 1mm ~ 0.1mm
What is the difference between uhf and vhf?
For the benefit of a beginner , the typical VHF communications band is considered around 100 to 170 MHz (2 meters is 144-148 MHz and 220 is 219-225 MHz), UHF around 400 to 500 MHz (70 cm is 420-450 MHz, 33 cm is 902-928 MHz, 23 cm is 1240-1300MHz, also ham bands at 2300-2310 MHz and 2390-2450 MHz).FM radio would be VHF (88 - 108 MHz esp. in USA, 76-108 MHz in some other parts of world (e.g. Japan))Cellular phones operate between 820- 920 MHz (approx) and 1805-1990 MHz with more spectrum added from time to time .When you get into 3 GHz (gigahertz or 3000 mhz) you are into microwave or RADAR frequencies .Another spectrum is called HF (High Frequency) , from 3-30 MHz. It was called HF because in the 1930's it was as high as they could go , but the label is still used in the Amateur Radio lexicon.From a US. Dept. of Commerce poster:VLF (Very Low Freq.) = 0 - 30kHz (audio)LF (Low Freq.) = 30 - 300 kHz (eg, Loran)MF (Medium Freq.) = 300kHz - 3MHz (eg, AM broadcast)HF (High Freq.) = 3MHz - 30MHz ("short wave")VHF (Very High Freq.) = 30MHz -300MHz (eg, FM broadcast, analog TV (VHF), civil aviation, analog public service)UHF (Ultra High Freq.) = 300MHz - 3GHz (eg, analog TV (UHF), analog cellphones)SHF (Super High Freq.) = 3GHz - 30GHz
How do satellites send imges to earth?
Satellites transmit signals using highly directional electromagnetic waves.Electromagnetic waves are used all the time in today's technology; microwaves use microwaves which are the same as mobile phones, televisions use ultrahigh frequency waves, visible light is in fact electromagnetic waves.....Where our mobile phones use multi-directional antenna satellites use parabolic dishes to produce unidirectional signals which are transmitted to receiver stations on the earth. A sky box is an example of one such receiver where only a download link can be established, i.e you cannot use your set top box to control the satellite._____________________________________________________________________In Addition (added by another user)Microwaves are used because their wavelength is long and thin, they don't refract much making them accurate. Furthermore, radio waves cannot be used as when under 30 MHz they reflect of the ionosphere and if they are above, their wavelength makes them refract too much. Strong signal strengths are needed as when above 30 GHz things like rain, dust etc reduce signal strength.Hope this helped.
