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YIG Sphere
Yttrium iron garnet spheres (YIG spheres) serve as magnetically tunable filters and resonators for microwave frequencies. YIG filters are used for their high Q factors, typically between 100 and 200. A sphere made from a single crystal of synthetic yttrium iron garnet acts as a resonator. The field from an electromagnet changes the resonance frequency of the sphere and hence the frequency it will allow to pass. The advantage of this type of filter is that the garnet can be tuned over a very wide frequency range by varying the strength of the magnetic field. Some filters can be tuned from 3 GHz up to 50 GHz. Construction The YIG spheres themselves are on the order of 0.5 mm in diameter and are manufactured from slightly larger cubes of diced material by tumbling, as is done in the manufacture of jewelry. The garnet is mounted on a ceramic rod, and a pair of small loops around the sphere couple fields into and out of the sphere; the loops are half-turns ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
YIG Microstrip Coupling
YIG or Yig may refer to: Organizations * Your Independent Grocer, a Canadian Grocery store * ''YMCA Youth in Government'', alternative name for YMCA Youth and Government Science and technology * Yttrium iron garnet, a synthetic garnet ** YIG sphere, an yttrium-iron-garnet-based microwave-frequency filter Various media *Yig (the Father of Serpents), a deity in H.P. Lovecraft's Cthulhu mythos **The Curse of Yig, short story by H.P.Lovecraft and Zealia Bishop **The Curse of Yig (book), collection of stories by Zealia Bishop {{Disambig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tumble Finishing
Tumble finishing, also known as tumbling or rumbling, is a technique for smoothing and polishing a rough surface on relatively small parts. In the field of metalworking, a similar process called barreling, or barrel finishing,Degarmo, p. 781. works upon the same principles. Tumbled stones are made with rock tumblers in a process very similar to the natural processes that produce "sea glass" or "beach glass". Stones Tumbling of rocks as a lapidary technique for rock polishing usually requires a plastic or rubber-lined barrel loaded with a consignment of rocks, all of similar or the same hardness, some abrasive grit, and a liquid lubricant. Silicon carbide grit is commonly used, and water is a universal lubricant. The barrel is then placed upon slowly rotating rails so that it rotates. The optimal speed of rotation depends on the size of the tumbler barrel and materials involved. Vibratory finishing process can be used instead. A well-chosen speed for stone polishing causes t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Filter Theory
Filter design is the process of designing a signal processing filter that satisfies a set of requirements, some of which may be conflicting. The purpose is to find a realization of the filter that meets each of the requirements to an acceptable degree. The filter design process can be described as an optimization problem. Certain parts of the design process can be automated, but an experienced designer may be needed to get a good result. The design of digital filters is a complex topic. Although filters are easily understood and calculated, the practical challenges of their design and implementation are significant and are the subject of advanced research. Typical design requirements Typical requirements which may be considered in the design process are: * Frequency response * Phase shift or group delay * impulse response * Causal filter required? * Stable filter required? * Finite (in duration) impulse response required? * Computational complexity * Technology The frequ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microwave Technology
Microwave is a form of electromagnetic radiation with wavelengths shorter than other radio waves but longer than infrared waves. Its wavelength ranges from about one meter to one millimeter, corresponding to frequency, frequencies between 300 MHz and 300 GHz, broadly construed. A more common definition in radio-frequency engineering is the range between 1 and 100 GHz (wavelengths between 30 cm and 3 mm), or between 1 and 3000 GHz (30 cm and 0.1 mm). In all cases, microwaves include the entire super high frequency, super high frequency (SHF) band (3 to 30 GHz, or 10 to 1 cm) at minimum. The boundaries between far infrared, terahertz radiation, microwaves, and ultra-high-frequency (UHF) are fairly arbitrary and differ between different fields of study. The prefix ' in ''microwave'' indicates that microwaves are small (having shorter wavelengths), compared to the radio waves used in prior radio technology. Frequencies in the micr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectrum Analyzer
A spectrum analyzer measures the magnitude of an input signal versus frequency within the full frequency range of the instrument. The primary use is to measure the power of the spectrum of known and unknown signals. The input signal that most common spectrum analyzers measure is electrical; however, spectral compositions of other signals, such as acoustic pressure waves and optical light waves, can be considered through the use of an appropriate transducer. Spectrum analyzers for other types of signals also exist, such as optical spectrum analyzers which use direct optical techniques such as a monochromator to make measurements. By analyzing the spectra of electrical signals, dominant frequency, power, distortion, harmonics, bandwidth, and other spectral components of a signal can be observed that are not easily detectable in time domain waveforms. These parameters are useful in the characterization of electronic devices, such as wireless transmitters. The display of a spec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Preselector
A preselector is a name for an electronic device that connects between a radio antenna and a radio receiver. The preselector is a band-pass filter that blocks troublesome out-of-tune frequencies from passing through from the antenna into the radio receiver (or preamplifier) that otherwise would be directly connected to the antenna. Purpose A preselector improves the performance of nearly any receiver, but is especially helpful to receivers with broadband front-ends that are prone to overload, such as scanners, wideband software-defined radio receivers, ordinary consumer-market shortwave and AM broadcast receivers – particularly with receivers operating below 10~20 MHz where static is pervasive. Sometimes faint signals that occupy a very narrow frequency span (such as radiotelegraph or 'CW') can be heard more clearly if the receiving bandwidth is made narrower than the narrowest that a general-purpose receiver may be able to tune; likewise, signals which i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ferrimagnetic
A ferrimagnetic material is a material that has populations of atoms with opposing magnetic moments, as in antiferromagnetism, but these moments are unequal in magnitude, so a spontaneous magnetization remains. This can for example occur when the populations consist of different atoms or ions (such as Fe2+ and Fe3+). Like ferromagnetic substances, ferrimagnetic substances are attracted by magnets and can be magnetized to make permanent magnets. The oldest known magnetic substance, magnetite (Fe3O4), is ferrimagnetic, but was classified as a ferromagnet before Louis Néel discovered ferrimagnetism in 1948. Since the discovery, numerous uses have been found for ferrimagnetic materials, such as hard-drive platters and biomedical applications. History Until the twentieth century, all naturally occurring magnetic substances were called ferromagnets. In 1936, Louis Néel published a paper proposing the existence of a new form of cooperative magnetism he called antiferro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loop Antenna
A loop antenna is a antenna (radio), radio antenna consisting of a loop or coil of wire, tubing, or other electrical conductor, that for transmitting is usually fed by a balanced power source or for receiving feeds a balanced load. Within this physical description there are two (possibly three) distinct types: ; #large_loop_anchor, Large loop antennas: Large loops are also called ''self-resonant loop antennas'' or ''full-wave loops''; they have a perimeter close to one or more whole wavelengths at the operating frequency, which makes them self-resonant at that frequency. They are the most antenna efficiency, efficient of all antenna types for both transmission and reception. Large loop antennas have a two-lobe radiation pattern at their first, full-wave resonance, peaking in both directions ''perpendicular'' to the plane of the loop. Large loops are the most antenna efficiency, efficient, by an order of magnitude, of all antenna designs of similar size. ; #halo_anchor, Halo ante ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jewelry
Jewellery (or jewelry in American English) consists of decorative items worn for personal adornment such as brooches, ring (jewellery), rings, necklaces, earrings, pendants, bracelets, and cufflinks. Jewellery may be attached to the body or the clothes. From a western perspective, the term is restricted to durable Ornament (art), ornaments, excluding flowers for example. For many centuries metal such as gold often combined with gemstones, has been the normal material for jewellery, but other materials such as glass, shells and other plant materials may be used. Jewellery is one of the oldest types of archaeological artefact – with 100,000-year-old beads made from ''Nassarius'' shells thought to be the oldest known jewellery. The basic forms of jewellery vary between cultures but are often extremely long-lived; in European cultures the most common forms of jewellery listed above have persisted since ancient times, while other forms such as adornments for the nose or ankle, impo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic Field
A magnetic field (sometimes called B-field) is a physical field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to the magnetic field. A permanent magnet's magnetic field pulls on ferromagnetic materials such as iron, and attracts or repels other magnets. In addition, a nonuniform magnetic field exerts minuscule forces on "nonmagnetic" materials by three other magnetic effects: paramagnetism, diamagnetism, and antiferromagnetism, although these forces are usually so small they can only be detected by laboratory equipment. Magnetic fields surround magnetized materials, electric currents, and electric fields varying in time. Since both strength and direction of a magnetic field may vary with location, it is described mathematically by a function (mathematics), function assigning a Euclidean vector, vector to each point of space, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electromagnet
An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. Electromagnets usually consist of wire (likely copper) wound into a electromagnetic coil, coil. A current through the wire creates a magnetic field which is concentrated along the center of the coil. The magnetic field disappears when the current is turned off. The wire turns are often wound around a magnetic core made from a ferromagnetic or ferrimagnetic material such as iron; the magnetic core concentrates the magnetic flux and makes a more powerful magnet. The main advantage of an electromagnet over a permanent magnet is that the magnetic field can be quickly changed by controlling the amount of electric current in the winding. However, unlike a permanent magnet, which needs no power, an electromagnet requires a continuous supply of current to maintain the magnetic field. Electromagnets are widely used as components of other electrical devices, such as Electric motor, motor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
