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Polarization-division Multiplexing
Polarization-division multiplexing (PDM) is a physical layer method for multiplexing signals carried on electromagnetic waves, allowing two channels of information to be transmitted on the same carrier frequency by using waves of two orthogonal polarization states. It is used in microwave links such as satellite television downlinks to double the bandwidth by using two orthogonally polarized feed antennas in satellite dishes. It is also used in fiber optic communication by transmitting separate left and right circularly polarized light beams through the same optical fiber. Radio Polarization techniques have long been used in radio transmission to reduce interference between channels, particularly at VHF frequencies and beyond. Under some circumstances, the data rate of a radio link can be doubled by transmitting two separate channels of radio waves on the same frequency, using orthogonal polarization. For example, in point to point terrestrial microwave links, the transmit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physical Layer
In the seven-layer OSI model of computer networking, the physical layer or layer 1 is the first and lowest layer; The layer most closely associated with the physical connection between devices. This layer may be implemented by a PHY chip. The physical layer provides an electrical, mechanical, and procedural interface to the transmission medium. The shapes and properties of the electrical connectors, the frequencies to broadcast on, the line code to use and similar low-level parameters, are specified by the physical layer. Role The physical layer defines the means of transmitting a stream of raw bits over a physical data link connecting network nodes. The bitstream may be grouped into code words or symbols and converted to a physical signal that is transmitted over a transmission medium. The physical layer consists of the electronic circuit transmission technologies of a network. It is a fundamental layer underlying the higher level functions in a network, and can be i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Waveguide
A waveguide is a structure that guides waves, such as electromagnetic waves or sound, with minimal loss of energy by restricting the transmission of energy to one direction. Without the physical constraint of a waveguide, wave intensities decrease according to the inverse square law as they expand into three-dimensional space. There are different types of waveguides for different types of waves. The original and most common meaningInstitute of Electrical and Electronics Engineers, “The IEEE standard dictionary of electrical and electronics terms”; 6th ed. New York, N.Y., Institute of Electrical and Electronics Engineers, c1997. IEEE Std 100-1996. d. Standards Coordinating Committee 10, Terms and Definitions; Jane Radatz, (chair)/ref> is a hollow conductive metal pipe used to carry high frequency radio waves, particularly microwaves. Dielectric waveguides are used at higher radio frequencies, and transparent dielectric waveguides and optical fibers serve as waveguides ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
XPIC
XPIC, or cross-polarization interference cancelling technology, is an algorithm to suppress mutual interference between two received streams in a Polarization-division multiplexing communication system. The cross-polarization interference canceller (known as XPIC) is a signal processing technique implemented on the demodulated received signals at the baseband level. It is typically necessary in Polarization Division Multiplexing systems: the data sources to be transmitted are coded and mapped into QAM modulating symbols at the system's symbol rate and upconverted to a carrier frequency, generating two radio streams radiated by a single dual-polarized antenna (see feed pattern of Parabolic antenna). A corresponding dual-polarized antenna is located at the remote site and connected to two receivers, which downconvert the radio streams into baseband signals (BB H, BB V). This multiplexing/demultiplexing technique is based on the expected discrimination between the two orthogonal p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alcatel-Lucent
Alcatel–Lucent S.A. () was a French–American global telecommunications equipment company, headquartered in Boulogne-Billancourt, France. It was formed in 2006 by the merger of France-based Alcatel and U.S.-based Lucent, the latter being a successor of AT&T's Western Electric and Bell Labs. In 2014, the Alcatel-Lucent group split into two: Alcatel-Lucent Enterprise, providing enterprise communication services, and Alcatel-Lucent, selling to communications operators. The enterprise business was sold to a Chinese company in the same year, and in 2016 Nokia purchased the rest of Alcatel-Lucent. The company focused on fixed, mobile and converged networking hardware, IP technologies, software and services, with operations in more than 130 countries. It had been named Industry Group Leader for Technology Hardware & Equipment sector in the 2014 Dow Jones Sustainability Indices review and listed in the 2014 Thomson Reuters Top 100 Global Innovators for the 4th consecutive year. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Huawei
Huawei Technologies Co., Ltd. ( ; ) is a Chinese multinational technology corporation headquartered in Shenzhen, Guangdong, China. It designs, develops, produces and sells telecommunications equipment, consumer electronics and various smart devices. The corporation was founded in 1987 by Ren Zhengfei, a former officer in the People's Liberation Army (PLA). Initially focused on manufacturing phone switches, Huawei has expanded its business to include building telecommunications networks, providing operational and consulting services and equipment to enterprises inside and outside of China, and manufacturing communications devices for the consumer market. Huawei has deployed its products and services in more than 170 countries and areas. It overtook Ericsson in 2012 as the largest telecommunications equipment manufacturer in the world, and overtook Apple in 2018 as the second-largest manufacturer of smartphones in the world, behind Samsung Electronics. In 2018, Huawei re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siae Microelettronica
SIAE MICROELETTRONICA is an Italian multinational corporation and a global supplier of telecom network equipments. It provides wireless backhaul and fronthaul solutions that comprise microwave and millimeter wave radio systems, along with fiber optics transmission systems provided by its subsidiary SM Optics. The company is headquartered in Milan, Italy, with 26 regional offices around the globe. Corporate history 1952–1970s: Origins and initial growth Edoardo Mascetti, after graduating in 1949 in Electrical Engineering at the Polytechnic University of Milan and working as electronic designer for Siemens, founded his company and named it SIAE, acronym for Società Italiana Apparecchiature Elettroniche The company manufactured measurement systems such as electro-mechanical testers, analog oscilloscopes, telephone system analyzers and signal generators. A 431A-model oscilloscope by SIAE was also part of the synthesizer in the Studio di fonologia musicale di Radio Milano ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Patch Antenna
A patch antenna is a type of antenna with a low profile, which can be mounted on a surface. It consists of a planar rectangular, circular, triangular, or any geometrical sheet or "patch" of metal, mounted over a larger sheet of metal called a ground plane. They are the original type of microstrip antenna described by Howell in 1972; the two metal sheets together form a resonant piece of microstrip transmission line with a length of approximately one-half wavelength of the radio waves. The radiation mechanism arises from fringing fields along the radiating edges. The radiation at the edges causes the antenna to act slightly larger electrically than its physical dimensions, so in order for the antenna to be resonant, a length of microstrip transmission line slightly shorter than one-half the wavelength at the frequency is used. The patch antenna is mainly practical at microwave frequencies, at which wavelengths are short enough that the patches are conveniently small. It is wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orthomode Transducer
An orthomode transducer (OMT) is a waveguide component that is commonly referred to as a ''polarisation duplexer''. ''Orthomode'' is a contraction of ''orthoganal mode''. Orthomode transducers serve either to combine or to separate two orthogonally polarized microwave signal paths. One of the paths forms the uplink, which is transmitted over the same waveguide as the received signal path, or downlink path. Such a device may be part of a very small aperture terminal (VSAT) antenna feed or a terrestrial microwave radio feed; for example, OMTs are often used with a feed horn to isolate orthogonal polarizations of a signal and to transfer transmit and receive signals to different ports. VSAT and satellite Earth station applications For VSAT modems the transmission and reception paths are at 90° to each other, or in other words, the signals are orthogonally polarized with respect to each other. This orthogonal shift between the two signal paths provides approximately an isola ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reflector (antenna)
An antenna reflector is a device that reflects electromagnetic waves. Antenna reflectors can exist as a standalone device for redirecting radio frequency (RF) energy, or can be integrated as part of an antenna assembly. Standalone reflectors The function of a standalone reflector is to redirect electro-magnetic (EM) energy, generally in the radio wavelength range of the electromagnetic spectrum. Common standalone reflector types are * corner reflector, which reflects the incoming signal back to the direction from which it came, commonly used in radar. * ''flat reflector,'' which reflects the signal such as a mirror and is often used as a passive repeater. Integrated reflectors When integrated into an antenna assembly, the reflector serves to modify the radiation pattern of the antenna, increasing gain in a given direction. Common integrated reflector types are * parabolic reflector, which focuses a beam signal into one point or directs a radiating signal into a beam. * a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microstrip
Microstrip is a type of electrical transmission line which can be fabricated with any technology where a conductor is separated from a ground plane by a dielectric layer known as the substrate. Microstrip lines are used to convey microwave-frequency signals. Typical realisation technologies are printed circuit board, alumina coated with a dielectric layer or sometimes silicon or some other similar technologies. Microwave components such as antennas, couplers, filters, power dividers etc. can be formed from microstrip, with the entire device existing as the pattern of metallization on the substrate. Microstrip is thus much less expensive than traditional waveguide technology, as well as being far lighter and more compact. Microstrip was developed by ITT laboratories as a competitor to stripline (first published by Grieg and Engelmann in the December 1952 IRE proceedings). The disadvantages of microstrip compared with waveguide are the generally lower power handling capacity ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quasi-TEM
Planar transmission lines are transmission lines with electrical conductor, conductors, or in some cases dielectric (insulating) strips, that are flat, ribbon-shaped lines. They are used to interconnect components on printed circuits and integrated circuits working at microwave frequencies because the planar type fits in well with the manufacturing methods for these components. Transmission lines are more than simply electrical cable, interconnections. With simple interconnections, the propagation of the electromagnetic wave along the wire is fast enough to be considered instantaneous, and the voltages at each end of the wire can be considered identical. If the wire is longer than a large fraction of a wavelength (one tenth is often used as a rule of thumb), these assumptions are no longer true and Telegrapher's equations, transmission line theory must be used instead. With transmission lines, the geometry of the line is precisely controlled (in most cases, the cross-section i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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