principle
The most basic resonant components is dielectric resonator. If you want to understand dielectric resonator principle of work must first understand metal waveguide with resonator.
Metal waveguide of general properties
Transmission electromagnetic energy or electromagnetic signals approach can be divided into two kinds, one kind is electromagnetic wave propagation in space or in the atmosphere, another kind is the spread of electromagnetic waves along the waveguide system. Initial human application of electromagnetic wave system is double waveguide transmission line, double transmission line basically use in lower frequency of occasions, when use frequency gradually improve the transmission line, double the transmission loss and radiation losses dramatically increased, in order to overcome radiation loss, adopted for micro-coaxial cable structure. But with the axis of the mode is still TEM mould, there must be two conductors, inside and outside to higher frequencies when loss of inner conductor become very serious. In microwave band namely FenMiBo segment and cm band people discovery, the use of a hollow tube for transmitting electromagnetic wave is feasible and convenient. In atc is not likely to spread TEM mode, so the method of TE mode or TM modes, this is called wave or metal waveguide. To short millimeter wave band and the micro millimeter wave band metal waveguide the cross-sectional area of the size too small, processing is not easy, so using dielectric waveguide as the transmission system. In wavelengths use fiber optic and optical waveguide is medium waveguide. Optical fiber abbreviation fiber have now become a major means of transmission of electromagnetic signals. In order to realize the approximate short-circuit boundary conditions can be used with high conductivity of conductor namely metal constitute the bounding surface, thus forming metal waveguide or called wave. Metal waveguide can by a root wave form, can also by multiple root wave form. Omitting conductor surface wear, can be boundary as short road. Waveguide wave is characteristic of the existence of a cut-off frequency, when working frequency higher than cutoff frequency longitudinal direction for fast when traveling wave, horizontal direction for standing wave, working frequency below cut-off frequency, longitudinal direction become attenuation field or gradually away games, horizontal direction is still standing wave. Metal waveguide propagation for omega c = T / (muon search-evade antagonistic) 1/2 = cT / (muon search-evade antagonistic) 1/2 or Fc = cT / 2 ∏ (muon search-evade antagonistic) 1/2 critical condition, electromagnetic wave in the medium wavelength is horizontal wavelength, namely lambda T = 2 ∏ / T = 1 / Fc (muon search-evade antagonistic) 1/2 corresponding critical condition in a vacuum wavelength is called critical wavelength. When the electromagnetic wave of angular big LinJieJiao vs long frequency, electromagnetic wave propagation in waveguide, conversely, waveguide is deadline. LinJieJiao wave number decided in waveguides sectional shape and dimension.
Metal waveguide wave impedance
Metal wall is by good conductors constitute rather than ideal conductor, so of electromagnetic field in waveguide is transmitted in certain will have power loss, causing the electromagnetic waves along the direction of propagation attenuation. Its attenuation constants for: а = 1 / four sigma delta * H2dL/P; Type, L for waveguide cross-section closed boundary, P for waveguide transmission of power flow, sigma for waveguide wall conductivity, The delta for waveguide wall materials of electromagnetic wave skin depth.
Completely by short road closed or open road surrounded by electromagnetic system is resonant system. Usually use high conductivity of conductor namely metal approximate to realize short-circuit the boundary conditions, this is metal wall resonator. When omitting chamber wall loss that chamber wall by the ideal conductor constitute, meanwhile lumen filled with nonconductive nondestructive medium, is the ideal resonator. In describing resonator before the following definitions; A rectangular waveguide and rectangular resonant cavity the bounding surface and moment coordinate system do surface superposition. A rectangular resonant cavity height is b, width is a. When in a rectangular waveguide > b, TE10 mold LinJieJiao wave number LinJieJiao frequency lowest minimum, namely, so TE10 mold for minimum mold. When b < a / 2 TE20 modules are times low mode, and when b > a / 2, TE01 mode for times low mode. When rectangular waveguide, called a = b, when TE10 square section waveguide modes and TE01 mould LinJieJiao equal frequency, right now the waveguide single-mode of transmission bandwidth is zero. Therefore square waveguide no actual use.
Cylindrical coordinate system of waveguide and resonator
The boundary surface and cylindrical coordinate system of plane.which coincide waveguide and resonator, they include circular waveguide, coaxial cables, cylindrical cavity, coaxial cavity, fan-shaped section waveguide and resonator etc bar system. Also includes radial line, horn waveguide blame such as bar waveguide system. Bar waveguide wavelength lambda of critical for: lambda cTM = 2 ∏ / TTM (muon search-evade antagonistic).
Quartz crystal resonator
Main encapsulation type
Quartz crystal resonator mainly by fits slice, pedestal, shell, silver glue, silver etc compositions. According to lead condition can be classified as straight inserts (lead) and SMT (no fuses) two types. Now common main encapsulation types are HC - 49U, HC - 49 / S, UM, UM - 1-4, UM - 5 and SMD.
Model naming methods
Quartz crystal resonator model named by the following three parts.
First part: with a Chinese phonetic alphabet said shell and shape of materials, such as metal shell by "J" says, plastic shell with "S" means, glass shell with "B" said.
The second part: with crystal cut type symbols and the first letter says quartz piece cutting orientation of type. Crystal cutting type and symbol table. Crystal cutting type and symbols
Characteristic parameters
Quartz crystal resonator main characteristic parameters have a nominal frequency, adjust the frequency offset, temperature frequency difference, the equivalent resistance, incentive level, load capacitance, static capacitor, LaoHuaLv and temperature range.
(1) the nominal frequency: under specified conditions, resonators assigned resonant center frequency.
(2) adjust frequency difference: under specified conditions, benchmark temperature the working frequency of the maximum relative nominal frequency deviation value.
(3) temperature frequency difference: under specified conditions, in the whole working temperature range, relative to the benchmark temperature working frequency allow deviation value.
4 base temperature: measurement quartz crystal resonator parameters when specified environment temperature. For thermostatic type quartz crystal resonator, generally for operating temperature range in the center of, For the thermostatic type quartz crystal resonator, ℃ + 2 for 25 ℃.
Will5 load resonant resistance: quartz crystal resonator and designated external capacitor in series, in load resonant frequency resistance.
6 incentive level: refers to quartz crystal resonator work when the consumption of effective power, it is said to joash the incentive condition of quartz crystal components of measurement. Common values have 0.1 mW 0.5 mW, 1mW, 2mW and 4mW,. In practice, incentive level can be adjusted, incentive strong easily when initial, incentive is too weak when frequency stability became worse, even afford vibration.
7 load capacitance: refers to quartz crystal resonator decide together load resonant frequency about effective outside capacitance. Load capacitance common values have 2OpF, 3OpF, 16pF, 5OpF and 1OOpF. Load capacitance can according to the specific conditions appropriate adjustments, through adjusting can generally will resonators the working frequency of transferred to the nominal value.
7 static capacitance: quartz crystal resonator between two pins static capacitance.
9 LaoHuaLv: refers to the increase of over time, quartz crystal aging changes arising from the error, the unit is 10 (6) years.
⑩ temperature range: refers to the working status to allow the change of environmental temperature range.
Main application
Metal waveguide with metal resonator is widely applied in FenMiBo, centimeter-wave and longer millimeter wave band. Due to the waveguide cross-section and resonator size and wavelength close, such as rectangular waveguide work in TE01 mode, its wide-brimmed size than 1/2 wavelength, so to short millimeter wave band and and submillimeter wave metal waveguide and resonator size too small, but difficult to manufacturing. In infrared bands or visible bands, namely wavelength for sub-micrometer range; application in metal waveguide or resonator more impossible. Therefore, dielectric waveguides and dielectric resonator rapidly developed and a wide range of applications. Although dielectric waveguides and dielectric resonator size also was in the wavelength of magnitude, but can be compared to use microfabrication means made small size. For example, sectional dimensions for sub-micrometer range; optic fiber and optical waveguide belong to medium waveguide. Metal waveguide the field can be regarded as the plane wave in conductors between surfaces reciprocating reflection is caused, medium the channel waveguide field also can be considered electromagnetic field in medium interface between refraction-such caused. Therefore, the dense medium surrounded by dredging medium forms medium waveguide. The ideal metal waveguide within a standing wave along the lateral electromagnetic field, in waveguide boundary outside approximate to ideal conductor, there is no electromagnetic field. At the medium waveguide within a standing wave along the lateral electromagnetic fields, but still exists in medium waveguide outside electromagnetic, it is dwindling along the lateral state, say with the modification field. In filling uniform media metal waveguide, TE and TM modes can die alone satisfy waveguide wall short-circuit boundary conditions, therefore can always will TE modes and TM modes, they can be divided in metal waveguide spread. When the metal waveguide filling two or more medium, or as part of a filling medium, electromagnetic field in addition to meeting the boundary conditions of conductor wall outside, still must satisfy the medium interface continuous condition. In a uniform filling two or more media circumstances can only have TE and TM's mixed mode HEM mode. By understanding the above content, then next to further understand the dielectric resonator.
Early in 1939, dielectric resonator concepts and theories have been put forward but because no find appropriate medium material, this theory to sleep more than 20 years, without obtaining the actual development, by the 1960's rutile porcelain contour dielectric constant 80100) ceramics (search-evade antagonistic hundredth of successfully developed, make dielectric resonator and begin to be attention. But because rutile porcelain temperature coefficient is too high, restricted its practical application. In the 1970s developed barium titanate department and zro2 is titanate dielectric ceramics, their high rate, low dissipation factor, low temperature coefficient, just make dielectric resonator practional utilization. Medium resonant instruments have small volume, light weight, high quality factor, good stability, etc. Especially suitable for application in microstrip circuit or microwave integrated circuits and millimeter wave is much attention and fast development. When the dielectric constant high medium with air interface approximate to open road, electromagnetic waves on the screen emission coefficient of close to 1. When the dielectric resonator surface as open wall, namely magnetic wall. So dielectric resonator become a homogeneous boundary conditions of the closed system, namely the equivalent open wall (magnetic wall) resonator.
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