frequency range - a term that is widely used in the course of physical and technical disciplines, particularly in radio.By this term is understood as the operating range of a device and a dedicated radio service for broadcasting a particular frequency range.And we can talk about the breakdown of all the radio frequency range.
international rules strictly regulate the use of different radio broadcast systems (including satellite), a well-defined range.This is dictated by the need to ensure interoperability of different systems and work to eliminate interference.
In the Radio Regulations, the area of land is divided into three large district.The first includes Europe, CIS, Russia, Mongolia and Africa.The second - the territory of America (both North and South).Third - South and South-East Asia, Australia, the Pacific region.In each area - its allocation of radio frequency bands.
For Satellite Communications Regulation provides frequency bands with symbols: L, S, C, X, Ku, Ka, K range from 1452 MHz to 86.0 GHz.The vast majority of satellite systems operating in bands C and Ku.Ka-band is actively being developed in Europe and America, but in our country is not widely used.
The efficiency of the antenna depends on the number of wavelengths that fit across the antenna.With increasing frequency, wavelength decreases (these values are inversely proportional) and receiving high-frequency signals are not required large antenna.C-band received by an antenna size of 2.5-4.5 meters, and for receiving waves to the desired size range antennas - only 10-15 cm. At the same size antennas operating in the high range, have higher gain.
In each broadcast transmitting station also has its own frequency range.There is a classification of radio waves over a range and wavelength.According to this wave are:
- Dekametricheskie with a wavelength of about 10 000-100 000 kilometers, the frequency of which are classified as very low (3 - 30 Hz).
- Megametricheskie (wavelength - 1000-10 000 kilometers), the frequency range - up to 300 Hz.
- Gektokilometrovye (100-1,000 kilometers length) relating to ultra-low frequencies (up to 3000 Hz).
- Extra-long (length - 10-100 kilometers) - is very low (up to 30 kHz).
- long (length is 1-10 kilometers) - low (up to 300 kHz).
- average (length 100-1000 meters) - average frequency of up to 3000 kHz.
- short, with a length of 10-100 meters - t. N.high frequency (30 MHz).
- Ultrashort or meter (length of 1-10 meters), very high (up to 300 MHz).
- Decimeter (length of 10-100 cm), ultra-high, up to 3000 MHz.
- centimeter (length 1-10 cm), ultra-high (up to 30 GHz).
- Millimeter (length 1-10 mm), very high (up to 300 GHz).
frequency range of 300-3000 GHz refers to t. N.hyper-high frequency range.
In the initial stages of development of radio waves used mainly long and super-long range.But they spread over the earth's surface, is strongly absorbed, required powerful transmitters.Stable reception is conducted at medium wavelengths, but they are difficult to ensure the transmission distance, and uses this range, basically, the local broadcasting with a radius of several hundred kilometers.
Short waves provide greater range, but are subject to interference and signal distortion.They are used mostly in the aviation and marine navigation and on the main lines connected.
The main advantage of the high frequency range - the possibility of antennas whose dimensions are comparable with the wavelength of the radiation is effective only under this condition.Construction of long-distance communication systems, based on the propagation of waves in sight, it was possible with the use of artificial satellites.
