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History Of Smart Antennas
The first smart antennas were developed for military communications and intelligence gathering. The growth of cellular telephone in the 1980s attracted interest in commercial applications. The upgrade to digital radio technology in the mobile phone, indoor wireless network, and satellite broadcasting industries created new opportunities for smart antennas in the 1990s, culminating in the development of the MIMO (multiple-input multiple-output) technology used in 4G wireless networks. Directional antennas The earliest success at tracking and controlling wireless signals relied on the antennas’ physical configuration and motion. The German inventor and physicist Karl F. Braun demonstrated beamforming for the first time in 1905. Braun created a phased array by positioning three antennas to reinforce radiation in one direction and diminish radiation in other directions. Guglielmo Marconi experimented with directional antennas in 1906. Directional antennas were rotated to detect an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smart Antennas
Smart antennas (also known as adaptive array antennas, digital antenna arrays, multiple antennas and, recently, MIMO) are antenna arrays with smart signal processing algorithms used to identify spatial signal signatures such as the direction of arrival (DOA) of the signal, and use them to calculate beamforming vectors which are used to track and locate the antenna beam on the mobile/target. Smart antennas should not be confused with reconfigurable antennas, which have similar capabilities but are single element antennas and not antenna arrays. Smart antenna techniques are used notably in acoustic signal processing, track and scan radar, radio astronomy and radio telescopes, and mostly in cellular systems like W-CDMA, UMTS, and LTE and 5G-NR. Smart antennas have many functions: DOA estimation, beamforming, interference nulling, and constant modulus preservation. Direction of arrival (DOA) estimation The smart antenna system estimates the direction of arrival of the signal, using ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MMIC
Monolithic microwave integrated circuit, or MMIC (sometimes pronounced "mimic"), is a type of integrated circuit (IC) device that operates at microwave frequencies (300 MHz to 300 GHz). These devices typically perform functions such as microwave mixing, power amplification, low-noise amplification, and high-frequency switching. Inputs and outputs on MMIC devices are frequently matched to a characteristic impedance of 50 ohms. This makes them easier to use, as cascading of MMICs does not then require an external matching network. Additionally, most microwave test equipment is designed to operate in a 50-ohm environment. MMICs are dimensionally small (from around 1 mm2 to 10 mm2) and can be mass-produced, which has allowed the proliferation of high-frequency devices such as cellular phones. MMICs were originally fabricated using gallium arsenide (GaAs), a III-V compound semiconductor. It has two fundamental advantages over silicon (Si), the traditional materi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bernard Widrow
Bernard Widrow (born December 24, 1929) is a U.S. professor of electrical engineering at Stanford University. He is the co-inventor of the Widrow–Hoff least mean squares filter (LMS) adaptive algorithm with his then doctoral student Ted Hoff. The LMS algorithm led to the ADALINE and MADALINE artificial neural networks and to the backpropagation technique. He made other fundamental contributions to the development of signal processing in the fields of geophysics, adaptive antennas, and adaptive filtering. A summary of his work is. He is the namesake of "Uncle Bernie's Rule": the training sample size should be 10 times the number of weights in a network. Biography This section is based on. Early life and education He was born in Norwich, Connecticut. While young, he was interested in electronics. During WWII, he found an entry on "Radios" in the ''World Book Encyclopedia,'' and built a one-tube radio. He entered MIT in 1947, studied electrical engineering and electr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Norbert Wiener
Norbert Wiener (November 26, 1894 – March 18, 1964) was an American computer scientist, mathematician, and philosopher. He became a professor of mathematics at the Massachusetts Institute of Technology ( MIT). A child prodigy, Wiener later became an early researcher in stochastic and mathematical noise processes, contributing work relevant to electronic engineering, electronic communication, and control systems. Wiener is considered the originator of cybernetics, the science of communication as it relates to living things and machines, with implications for engineering, systems control, computer science, biology, neuroscience, philosophy, and the organization of society. His work heavily influenced computer pioneer John von Neumann, information theorist Claude Shannon, anthropologists Margaret Mead and Gregory Bateson, and others. Wiener is credited as being one of the first to theorize that all intelligent behavior was the result of feedback mechanisms, tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio-frequency Identification
Radio-frequency identification (RFID) uses electromagnetic fields to automatically Automatic identification system, identify and Tracking system, track tags attached to objects. An RFID system consists of a tiny radio transponder called a tag, a radio receiver, and a transmitter. When triggered by an electromagnetic interrogation pulse from a nearby RFID reader device, the tag transmits digital data, usually an Identifier, identifying inventory number, back to the reader. This number can be used to track inventory goods. Passive tags are powered by energy from the RFID reader's interrogating radio waves. Active tags are powered by a battery and thus can be read at a greater range from the RFID reader, up to hundreds of meters. Unlike a barcode, the tag does not need to be within the Line-of-sight propagation, line of sight of the reader, so it may be embedded in the tracked object. RFID is one method of automatic identification and data capture (AIDC). RFID tags are used in m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Van Atta Array
A Van Atta array is a type of passive retrodirective phased array antenna which redirects (rather than reflects) a signal back in the direction from which it came. It was first described by L. C. van Atta in his 1959 patent. The signal can be modulated by the redirecting host for purposes such as radio-frequency identification and traffic control (radar target echo enhancement). A 2023 paper describes the extension of the van Atta antenna principle to underwater acoustic communication. References See also * Retroreflector A retroreflector (sometimes called a retroflector or cataphote) is a device or surface that reflects light or other radiation back to its source with minimum scattering. This works at a wide range of angle of incidence (optics), angle of incidenc ... Radio frequency antenna types {{radio-comm-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retrodirectivity
A retrodirective antenna is an antenna that transmits the signal back in the same direction it came from. This is based on the principle of self-phase conjugation of the input signal. Directivity depends on relative phases of signal radiated from different elements. Arrayed antenna consist of multiple, identical radiating elements. Retrodirectivity can be achieved entirely passively with the use of a van Atta array. Retrodirectivity can also be achieved with phase conjugation by geometric placement of antenna elements (also known as heterodyning). Phase conjugation is obtained by mixing with LO (local oscillator) frequencies twice that of the incoming signal. Applications Using retrodirectivity allows for faster acquisition (up to twelve times faster) than phased array antennas, and with up to twenty-five times the power output. The key advantages of retrodirective antennas over phased array antennas are less signal processing Signal processing is an electrical engineeri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Murchison Widefield Array
The Murchison Widefield Array (MWA) is a joint project between an international consortium of organisations to construct and operate a low-frequency radio array. 'Widefield' refers to its very large field of view (on the order of 30 degrees across). Operating in the frequency range 70–300 MHz, the main scientific goals of the MWA are to detect neutral atomic Hydrogen emission from the cosmological Epoch of Reionization (EoR), to study the Sun, the heliosphere, the Earth's ionosphere, and radio transient phenomena, as well as map the extragalactic radio sky. It is located at the Murchison Radio-astronomy Observatory (MRO). Along with the Australian Square Kilometre Array Pathfinder (ASKAP), also at the MRO, and two radio telescopes in South Africa, the Hydrogen Epoch of Reionization Array (HERA) and MeerKAT, the MWA is one of four precursors to the international project known as the Square Kilometre Array (SKA). Development The MWA was to be situated at Mileura St ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Karl Jansky
Karl Guthe Jansky (October 22, 1905 – February 14, 1950) was an American physicist and radio engineer who in April 1933 first announced his discovery of radio waves emanating from the Milky Way in the constellation Sagittarius. He is considered one of the founding figures of radio astronomy. Early life Karl Guthe Jansky was born 1905 in what was then the Territory of Oklahoma where his father, Cyril M. Jansky, was dean of the college of engineering at the University of Oklahoma at Norman. Cyril M. Jansky, born in Wisconsin of Czech immigrants, had started teaching at the age of sixteen. He was a teacher throughout his active life, retiring as professor of electrical engineering at the University of Wisconsin. He was an engineer with a strong interest in physics, a trait passed on to his sons. Karl Jansky was named after Dr. Karl Eugen Guthe, a professor of physics at the University of Michigan who had been an important mentor to Cyril M. Jansky. Karl Jansky's mother, bo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PAVE PAWS
PAVE PAWS (PAVE Phased Array Warning System) is a complex Cold War early warning radar and computer system developed in 1980 to "detect and characterize a sea-launched ballistic missile attack against the United States". The first solid-state phased array deployed used a pair of Raytheon AN/FPS-115 phased array radar sets at each site to cover an azimuth angle of 240 degrees. In accordance with the Joint Electronics Type Designation System, the "AN/FPS-115" designation represents the 115th design of an Army-Navy fixed radar(pulsed) electronic device for searching. Two sites were deployed in 1980 at the periphery of the contiguous United States, then two more in 1987–95 as part of the United States Space Surveillance Network. One system was sold to Taiwan and is still in service. Mission The radar was built in the Cold War to give early warning of a nuclear attack, to allow time for US bombers to get off the ground and land-based US missiles to be launched, to decrease ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hughes Electronics
Hughes Electronics Corporation was formed in 1985, when Hughes Aircraft was sold by the Howard Hughes Medical Institute to General Motors for $5.2 billion. Surviving parts of Hughes Electronics are today known as DirecTV Group, while the automotive divisions became Aptiv. On June 5, 1985, General Motors was announced as the winner of a secretive five month, sealed-bid auction. Other bidders included Ford Motor Company and Boeing. The purchase was completed on December 20, 1985, for an estimated $5.2 billion, with $2.7 billion in cash and the remainder in 50 million shares of GM Class H stock. On December 31, 1985, General Motors merged Hughes Aircraft with its Delco Electronics unit to form Hughes Electronics Corporation, an independent subsidiary. In August 1992, Hughes Aircraft completed its purchase of General Dynamics' missile businesses for $450 million. This brought the Tomahawk Cruise Missile, Advanced Cruise Missile, Standard missile, Stinger missile, Phalanx Clos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
General Electric
General Electric Company (GE) was an American Multinational corporation, multinational Conglomerate (company), conglomerate founded in 1892, incorporated in the New York (state), state of New York and headquartered in Boston. Over the years, the company had multiple divisions, including GE Aerospace, aerospace, GE Power, energy, GE HealthCare, healthcare, lighting, locomotives, appliances, and GE Capital, finance. In 2020, GE ranked among the Fortune 500, ''Fortune'' 500 as the 33rd largest firm in the United States by gross revenue. In 2023, the company was ranked 64th in the Forbes Global 2000, ''Forbes'' Global 2000. In 2011, GE ranked among the Fortune 20 as the 14th most profitable company, but later very severely underperformed the market (by about 75%) as its profitability collapsed. Two employees of GE—Irving Langmuir (1932) and Ivar Giaever (1973)—have been awarded the Nobel Prize. From 1986 until 2013, GE was the owner of the NBC television network through its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
