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Stripline Geometry
Stripline is a transverse electromagnetic (TEM) transmission line medium invented by Robert M. Barrett of the Air Force Cambridge Research Centre in the 1950s. Stripline is the earliest form of planar transmission line. Description A stripline circuit uses a flat strip of metal which is sandwiched between two parallel ground planes. The insulating material of the substrate forms a dielectric. The width of the strip, the thickness of the substrate and the relative permittivity of the substrate determine the characteristic impedance of the strip which is a transmission line. As shown in the diagram, the central conductor need not be equally spaced between the ground planes. In the general case, the dielectric material may be different above and below the central conductor. To prevent the propagation of unwanted modes, the two ground planes must be shorted together. This is commonly achieved by a row of vias running parallel to the strip on each side. Like coaxial cable, str ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air Stripline
Air stripline is a form of electrical planar transmission line whereby a conductor in the form of a thin metal strip is suspended between two ground planes. The idea is to make the dielectric essentially air. Mechanical support of the line may be a thin substrate, periodical insulated supports, or the device connectors and other electrical items. Air stripline is most commonly used at microwave frequencies, especially in the C band. Its advantage over standard stripline and other planar technologies is that its air dielectric avoids dielectric loss. Many useful circuits can be constructed with air stripline and it is also easier to achieve strong coupling between components in this technology than with other planar formats. It was invented by Robert M. Barrett in the 1950s. Structure Air stripline is a form of stripline using air as the dielectric material between the central conductor and the ground planes. Using air as the dielectric has the advantage that it avoids th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthur A
Arthur is a common male given name of Brythonic origin. Its popularity derives from it being the name of the legendary hero King Arthur. The etymology is disputed. It may derive from the Celtic ''Artos'' meaning “Bear”. Another theory, more widely believed, is that the name is derived from the Roman clan '' Artorius'' who lived in Roman Britain for centuries. A common spelling variant used in many Slavic, Romance, and Germanic languages is Artur. In Spanish and Italian it is Arturo. Etymology The earliest datable attestation of the name Arthur is in the early 9th century Welsh-Latin text ''Historia Brittonum'', where it refers to a circa 5th to 6th-century Briton general who fought against the invading Saxons, and who later gave rise to the famous King Arthur of medieval legend and literature. A possible earlier mention of the same man is to be found in the epic Welsh poem ''Y Gododdin'' by Aneirin, which some scholars assign to the late 6th century, though this is still a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Power Dividers And Directional Couplers
Power dividers (also power splitters and, when used in reverse, power combiners) and directional couplers are passive devices used mostly in the field of radio technology. They couple a defined amount of the electromagnetic power in a transmission line to a port enabling the signal to be used in another circuit. An essential feature of directional couplers is that they only couple power flowing in one direction. Power entering the output port is coupled to the isolated port but not to the coupled port. A directional coupler designed to split power equally between two ports is called a hybrid coupler. Directional couplers are most frequently constructed from two coupled transmission lines set close enough together such that energy passing through one is coupled to the other. This technique is favoured at the microwave frequencies where transmission line designs are commonly used to implement many circuit elements. However, lumped component devices are also possible at lower ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distributed Element Filter
A distributed-element filter is an electronic filter in which capacitance, inductance, and resistance (the elements of the circuit) are not localised in discrete capacitors, inductors, and resistors as they are in conventional filters. Its purpose is to allow a range of signal frequencies to pass, but to block others. Conventional filters are constructed from inductors and capacitors, and the circuits so built are described by the lumped element model, which considers each element to be "lumped together" at one place. That model is conceptually simple, but it becomes increasingly unreliable as the frequency of the signal increases, or equivalently as the wavelength decreases. The distributed-element model applies at all frequencies, and is used in transmission-line theory; many distributed-element components are made of short lengths of transmission line. In the distributed view of circuits, the elements are distributed along the length of conductors and are inextricably mixed to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Printed Circuit Board
A printed circuit board (PCB; also printed wiring board or PWB) is a medium used in electrical and electronic engineering to connect electronic components to one another in a controlled manner. It takes the form of a laminated sandwich structure of conductive and insulating layers: each of the conductive layers is designed with an artwork pattern of traces, planes and other features (similar to wires on a flat surface) etched from one or more sheet layers of copper laminated onto and/or between sheet layers of a non-conductive substrate. Electrical components may be fixed to conductive pads on the outer layers in the shape designed to accept the component's terminals, generally by means of soldering, to both electrically connect and mechanically fasten them to it. Another manufacturing process adds vias: plated-through holes that allow interconnections between layers. Printed circuit boards are used in nearly all electronic products. Alternatives to PCBs include wire ... [...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] |
Inverted-F Antenna
An inverted-F antenna is a type of antenna used in wireless communication, mainly at UHF and microwave frequencies. It consists of a monopole antenna running parallel to a ground plane and grounded at one end. The antenna is fed from an intermediate point a distance from the grounded end. The design has two advantages over a simple monopole: the antenna is shorter and more compact, allowing it to be contained within the case of the mobile device, and it can be impedance matched to the feed circuit by the designer, allowing it to radiate power efficiently, without the need for extraneous matching components. The inverted-F antenna was first conceived in the 1950s as a bent-wire antenna. However, its most widespread use is as a planar inverted-F antenna (PIFA) in mobile wireless devices for its space saving properties. PIFAs can be printed using the microstrip format, a widely used technology that allows printed RF components to be manufactured as part of the same printed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eugene Fubini
Eugene Ghiron Fubini (April 19, 1913 - August 5, 1997) was a physicist, academic, and scholar who participated in research that led to the creation of the first atomic bomb and also served as United States Assistant Secretary of Defense in the Kennedy and Johnson Administrations. He is well known as adefense policy maker of the Cold War and was the principal manager of the Pentagon's $7 billion annual research and development programs. He later served as group Vice president and chief scientist at International Business Machines Corporation from 1965 to 1969. Early life and education Eugene was born to Guido Fubini, known for Fubini's theorem and the Fubini–Study metric. Eugene later immigrated from Italy to the United States. He graduated from the Technical Institute of Turin and earned a doctorate in physics at the University of Turin, where he studied under Nobel laureate Enrico Fermi. Career In 1939, and in 1942 joined the war effort, working with America despite his nati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrical Resistance
The electrical resistance of an object is a measure of its opposition to the flow of electric current. Its reciprocal quantity is , measuring the ease with which an electric current passes. Electrical resistance shares some conceptual parallels with mechanical friction. The SI unit of electrical resistance is the ohm (), while electrical conductance is measured in siemens (S) (formerly called the 'mho' and then represented by ). The resistance of an object depends in large part on the material it is made of. Objects made of electrical insulators like rubber tend to have very high resistance and low conductance, while objects made of electrical conductors like metals tend to have very low resistance and high conductance. This relationship is quantified by resistivity or conductivity. The nature of a material is not the only factor in resistance and conductance, however; it also depends on the size and shape of an object because these properties are extensive rather than i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrical Reactance
In electrical circuits, reactance is the opposition presented to alternating current by inductance or capacitance. Greater reactance gives smaller current for the same applied voltage. Reactance is similar to resistance in this respect, but does not lead to dissipation of electrical energy as heat; instead, energy is momentarily stored in the reactance, and a quarter-cycle later returned to the circuit. Reactance is used to compute amplitude and phase changes of sinusoidal alternating current going through a circuit element. Like resistance, reactance is measured in ohms, with positive values indicating ''inductive'' reactance and negative indicating ''capacitive'' reactance. It is denoted by the symbol X. An ideal resistor has zero reactance, whereas ideal inductors and capacitors have zero resistance. As frequency increases, inductive reactance increases and capacitive reactance decreases. Comparison to resistance Reactance is similar to resistance in that larger reactan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stub (electronics)
In microwave and radio-frequency engineering, a stub or resonant stub is a length of transmission line or waveguide that is connected at one end only. The free end of the stub is either left open-circuit, or short-circuited (as is always the case for waveguides). Neglecting transmission line losses, the input impedance of the stub is purely reactive; either capacitive or inductive, depending on the electrical length of the stub, and on whether it is open or short circuit. Stubs may thus function as capacitors, inductors and resonant circuits at radio frequencies. The behaviour of stubs is due to standing waves along their length. Their reactive properties are determined by their physical length in relation to the wavelength of the radio waves. Therefore, stubs are most commonly used in UHF or microwave circuits in which the wavelengths are short enough that the stub is conveniently small. They are often used to replace discrete capacitors and inductors, because at UHF an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
