Conductive channels of communication | engineering, technical sciences, materials, fooddesign papers, development
Transmission of information can be used and high-voltage power transmission lines. The merits of these can indicate their strength, strict supervision on them. The disadvantages of these lines appear significant interference, fooddesign the use of special separation devices, their planned and emergency shutdown.
In the high frequency range (above 12 kHz), any real line is considered as a line with distributed parameters. These include open lines with two or four wires, coaxial lines and waveguides.
- Symmetrical feeders. Used mainly in the shortwave and FM. The simplest symmetrical two-wire feeder is open line (Figure 2.1). It consists of two parallel copper wires arranged symmetrically with respect to ground and the surrounding objects. Constructive this is achieved through the use of remote v.ch. insulators. fooddesign Wave resistance depends exclusively on the geometric dimensions of the section of wires and is given by
Symmetrical belt cords are made of two parallel wires, pressed into a plastic insulating tape (Fig. 2.1 b). Most often the two wires are stranded, composed of seven tin or silver wire with a diameter of 0,3 mm.
Ribbon cables are manufactured with relatively high wave resistance - 240 or 300 W. Although unshielded, fooddesign have some protection against the ingress of external interference. Penetration of interference depends on the symmetry of the two wires to the ground and surrounding objects. It can be significantly improved by twist about its axis with 3-5 twists per meter.
Such a device has a circular symmetrical cable. It is made of two monofilament wires, placed fooddesign symmetrically in a cylindrical v.ch. insulation that is wrapped sequentially by a spirally wound copper shielding tape and insulating jacket (Fig. 2.1v). Its wave resistance averages 120 W.
Circular symmetric cable has a relatively high attenuation as the electromagnetic field transmitted v.ch. energy is concentrated entirely in the cable dielectric. But in return, these cables are very well protected against the penetration of external disturbances by grounding the shield cover.
- Coaxial cable. It consists of two conductors situated in each other (Fig. 2.2a). The outside has a large diameter and hollow. Inside is located another conductor, fooddesign but with a significantly smaller diameter. There is mutual concentrically. Between the two conductors to form an electric field whose field lines are radial, while the magnetic field lines are concentric. The electromagnetic field is distributed between fooddesign two conductors, as used for the outer screen and almost no antenna effect, ie either broadcast or receive electromagnetic waves.
Waveguides are metal tubes with a rectangular or circular cross-section, in which spread electromagnetic field (Fig. 2.3 a). Inside of the tubes are gold or silver. They are used to transmit v.ch. energy centimeter and millimeter.
A waveguide with rectangular fooddesign cross section, may be represented as a line, which adheres to the top and bottom "Metal Insulator" (Fig. 2.3b). They do not violate modes. If you increase fooddesign their number to infinity to give waveguide. It is clear that the wider walls should have a size a = 0,5 l, it will not act as insulators. fooddesign Increase the amount it can be assumed since then it is believed that the conductor takes excess of 0,5 l. Such a waveguide provides fooddesign a distribution of the wave length of which is less than 2a. It is called the critical wavelength l kp = 2 a.
Optics (optical) lines. Represent optical fiber with very thin double layer fiber with a circular section. The size of the cross section of the fiber must be commensurate with the wavelength; its core has a diameter of 5 to 50 mm, and the sheath 100-30 mm.
Losses fooddesign in optical cables due to absorption and scattering. Uptake depends on the purity of quartz glass, while the scattering due to the unevenness formed by the melting or cooling of the glass.
Insertion in a glass designed for the optical fiber depends on the wavelength. Therefore prefer the following lengths: 0,85 mm, 1,3 mm and 1,55 mm. Optical cables for longer wavelengths have less attenuation. For example, fooddesign for l = 0,85 mm attenuation is about 2-3 dB / km, for a 1,3 mm an estimated 1 dB / km and 1,55 mm less than 0,5 dB / km. The use of waves of greater length is associated with certain difficulties.
The width of the transmitted bandwidth of the fiber depends on its length. A short pulse after passing through the cable expands. This is equivalent to a narrow bandwidth. For this reason, it is expressed in MHz.km. <
Transmission of information can be used and high-voltage power transmission lines. The merits of these can indicate their strength, strict supervision on them. The disadvantages of these lines appear significant interference, fooddesign the use of special separation devices, their planned and emergency shutdown.
In the high frequency range (above 12 kHz), any real line is considered as a line with distributed parameters. These include open lines with two or four wires, coaxial lines and waveguides.
- Symmetrical feeders. Used mainly in the shortwave and FM. The simplest symmetrical two-wire feeder is open line (Figure 2.1). It consists of two parallel copper wires arranged symmetrically with respect to ground and the surrounding objects. Constructive this is achieved through the use of remote v.ch. insulators. fooddesign Wave resistance depends exclusively on the geometric dimensions of the section of wires and is given by
Symmetrical belt cords are made of two parallel wires, pressed into a plastic insulating tape (Fig. 2.1 b). Most often the two wires are stranded, composed of seven tin or silver wire with a diameter of 0,3 mm.
Ribbon cables are manufactured with relatively high wave resistance - 240 or 300 W. Although unshielded, fooddesign have some protection against the ingress of external interference. Penetration of interference depends on the symmetry of the two wires to the ground and surrounding objects. It can be significantly improved by twist about its axis with 3-5 twists per meter.
Such a device has a circular symmetrical cable. It is made of two monofilament wires, placed fooddesign symmetrically in a cylindrical v.ch. insulation that is wrapped sequentially by a spirally wound copper shielding tape and insulating jacket (Fig. 2.1v). Its wave resistance averages 120 W.
Circular symmetric cable has a relatively high attenuation as the electromagnetic field transmitted v.ch. energy is concentrated entirely in the cable dielectric. But in return, these cables are very well protected against the penetration of external disturbances by grounding the shield cover.
- Coaxial cable. It consists of two conductors situated in each other (Fig. 2.2a). The outside has a large diameter and hollow. Inside is located another conductor, fooddesign but with a significantly smaller diameter. There is mutual concentrically. Between the two conductors to form an electric field whose field lines are radial, while the magnetic field lines are concentric. The electromagnetic field is distributed between fooddesign two conductors, as used for the outer screen and almost no antenna effect, ie either broadcast or receive electromagnetic waves.
Waveguides are metal tubes with a rectangular or circular cross-section, in which spread electromagnetic field (Fig. 2.3 a). Inside of the tubes are gold or silver. They are used to transmit v.ch. energy centimeter and millimeter.
A waveguide with rectangular fooddesign cross section, may be represented as a line, which adheres to the top and bottom "Metal Insulator" (Fig. 2.3b). They do not violate modes. If you increase fooddesign their number to infinity to give waveguide. It is clear that the wider walls should have a size a = 0,5 l, it will not act as insulators. fooddesign Increase the amount it can be assumed since then it is believed that the conductor takes excess of 0,5 l. Such a waveguide provides fooddesign a distribution of the wave length of which is less than 2a. It is called the critical wavelength l kp = 2 a.
Optics (optical) lines. Represent optical fiber with very thin double layer fiber with a circular section. The size of the cross section of the fiber must be commensurate with the wavelength; its core has a diameter of 5 to 50 mm, and the sheath 100-30 mm.
Losses fooddesign in optical cables due to absorption and scattering. Uptake depends on the purity of quartz glass, while the scattering due to the unevenness formed by the melting or cooling of the glass.
Insertion in a glass designed for the optical fiber depends on the wavelength. Therefore prefer the following lengths: 0,85 mm, 1,3 mm and 1,55 mm. Optical cables for longer wavelengths have less attenuation. For example, fooddesign for l = 0,85 mm attenuation is about 2-3 dB / km, for a 1,3 mm an estimated 1 dB / km and 1,55 mm less than 0,5 dB / km. The use of waves of greater length is associated with certain difficulties.
The width of the transmitted bandwidth of the fiber depends on its length. A short pulse after passing through the cable expands. This is equivalent to a narrow bandwidth. For this reason, it is expressed in MHz.km. <
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