CN108011171B - Broadband dielectric resonator - Google Patents
Broadband dielectric resonator Download PDFInfo
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- CN108011171B CN108011171B CN201711233522.6A CN201711233522A CN108011171B CN 108011171 B CN108011171 B CN 108011171B CN 201711233522 A CN201711233522 A CN 201711233522A CN 108011171 B CN108011171 B CN 108011171B
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Abstract
The invention provides a broadband dielectric resonator, which comprises an upper resonator plate, a lower resonator plate, a dielectric material to be tested and a coupling ring, wherein the upper resonator plate, the lower resonator plate and the dielectric material to be tested form a dielectricA mass resonance portion; the upper plate and the lower plate of the resonator are made of hard dielectric substrates; the hard dielectric substrate is provided with the metal coating on the surface facing the dielectric material to be detected, and the metal coating is engraved with the gap structure0npA modal spectrum.
Description
Technical Field
The invention belongs to the technical field of microwaves, and particularly relates to TE for complex dielectric constant test0npA mode broadband dielectric resonator.
Background
TE0npThe mode dielectric resonator is a microwave resonator, can be used for measuring complex dielectric constant of dielectric materials, testing conductivity of microwave broadband and the like, has the characteristics of rapidness, reliability, accuracy, no damage, automatic measurement and the like, and has certain practicability. The tunable optical fiber works in a TE mode and has the advantages of simple and stable field structure, no chromatic dispersion, wide working frequency band and the like. The common dielectric resonator is composed of an upper metal cover plate, a lower metal cover plate and a circular dielectric material to be measured, and the strongest magnetic field positions on two sides of the dielectric material to be measured are excited by a coupling ring to generate resonance. Selecting different n,p can obtain different mode resonant frequencies, thereby obtaining multiple TEs0npThe working mode is that a plurality of modes can be realized by using one resonator, and a plurality of discrete main mode working frequency points are covered in a wider frequency band range.
Measuring the complex dielectric constant of the medium by a dielectric resonator method, wherein the selected working mode is TE0npAnd (5) molding. Using dielectric material to be tested to TE0npAnd (3) disturbing the mode to obtain resonance parameters before and after the sample is loaded, and calculating to obtain the complex dielectric constant of the dielectric material to be measured. However, in practice, a great deal of non-TE is generated in the dielectric material to be measured and the periphery thereof0npResonant modes of the mode, resulting in a resonant mode at the opposite TE0npThe resonance parameters cannot be accurately judged when being measured, and finally the test result is inaccurate. Especially when the computer software is used for rapid measurement, the excessive mixed mode interference makes the computer unable to directly find the correct high-order TE0npThe resonant frequency of the mode is described in the article "measurement of dielectric parameter frequency response characteristic and frequency temperature coefficient of dielectric resonator" of Tangzong xi011Measuring the complex dielectric constant in the mode, calculating the resonant frequency of the higher-order mode, and performing higher-order TE near the resonant frequency0npThe parameters of the mode are measured to calculate the complex permittivity at that frequency. Finding a non-TE is likely to occur without knowing the frequency response of the electromagnetic parameters of the medium0npAnd thus results in errors in test results. Therefore, how to suppress and eliminate TE0npThe interference modes other than the mode become the key of the design of the dielectric resonator. TE0npCharacteristic equation of model
In the formula
A and L are respectively the radius and height of the cylindrical dielectric material to be measured, f0Is the resonant frequency, mu0、0Are respectively permeability and dielectric constant in vacuum'rIs the relative complex dielectric constant of the dielectric material to be measured, p is the number of half-wavelengths of the axial field of the dielectric resonator, Jp(u)、Kp(v) P-order Bessel functions of the first kind and Bessel functions of the second kind, respectively, where u ═ kc1a,v＝kc2a, after the dimension and the resonant frequency of the dielectric material to be measured are measured, solving the characteristic equation sets (1) - (3) to obtain the complex dielectric constant'r。
According to the characteristic equation, the sizes of the resonant frequencies of different modes are related to the size and the electromagnetic parameters of the dielectric material to be detected, the size of the dielectric material to be detected is optimally selected through the estimated value of the complex dielectric constant of the dielectric material to be detected, a sample with a proper corresponding size is manufactured, and a part of interference modes can be far away from a working frequency band. By adding the cylindrical cavity shell and coating the wave-absorbing material on the inner wall, a closed space is formed, so that the interference of external electromagnetic waves on the closed space can be prevented, a high-order mode is formed, and the leakage of the electromagnetic waves can be prevented. However, there are still a lot of interference patterns existing in the operating frequency band, which severely limits the available bandwidth, so how to suppress the interference patterns as much as possible without affecting the operating mode, and obtain a relatively pure TE0npThe mode becomes a key problem for designing a dielectric resonator method to measure the complex dielectric constant.
Disclosure of Invention
The invention aims to provide a method for working in TE, which can inhibit interference mode, improve measurement accuracy0npA broadband dielectric resonator of a mode.
The technical scheme of the invention is as follows:
a broadband dielectric resonator comprises an upper resonator plate, a lower resonator plate, a dielectric material to be measured and two coupling rings, wherein the dielectric material to be measured and the two coupling rings are arranged between the upper resonator plate and the lower resonator plate; the upper plate and the lower plate of the resonator are parallel to each other and are made of circular hard dielectric substrates; the dielectric material to be measured is a cylinder which is vertical to the circle centers of the upper plate and the lower plate of the resonator, the two coupling rings are distributed on the two sides of the dielectric material to be measured in opposite directions along the diameter direction of the upper plate and the lower plate of the resonator and point to the circle centers, one surfaces of the upper plate and the lower plate of the resonator, which face the dielectric material to be measured, are provided with metal coating layers, and the other surfaces are coated with wave-absorbing; the metal coating is carved with circular gap structure, and the gap structure is a circular gap concentric with the upper and lower plates of the resonator.
The upper and lower plates of the resonator are made of hard dielectric substrates, and the resonator has the main advantages that: the processing is convenient and the cost is low. The side of the metal cladding facing the medium material to be measured is provided with a metal cladding, and a gap structure is carved on the metal cladding and is mainly used for cutting off a current line in a non-working mode, so that electromagnetic waves in the non-working mode cannot form resonance due to the fact that the electromagnetic waves cannot form a current loop, and are radiated out by the gap. And a wave-absorbing material is coated on one side of the hard medium substrate, which is opposite to the medium material to be detected, and is used for absorbing the electromagnetic wave radiated from the gap structure in the non-working mode, so that the non-working mode is better inhibited.
Preferably, the thickness of the metal coating is greater than the skin depth of the electromagnetic wave at the working frequency point of the dielectric resonator, and the surface of the metal coating is subjected to gold plating treatment. The surface roughness of the plating layer is better than grade 7. The optimal mode is based on the advantages of good conductivity, wear resistance, oxidation resistance and the like of the gold-plated layer, can well protect the copper at the bottom layer, improves the performance and prolongs the service life.
As a preferred mode, the gap structure is a plurality of circles of concentric circular gaps uniformly arranged in the radius direction at the circle centers of the upper plate and the lower plate of the resonator, 5-10 gaps are arranged in the radius range of the medium material to be measured, and the preferred structure is based on TE0npThe electromagnetic field distribution of the mode is designed, and the current line of the mode is a circle with the center of the dielectric material to be measured as the center of the circle, so that the annular gap structure is adopted, and non-TE can be cut off0npCurrent line of mode to be notTE0npThe mode is effectively inhibited, and the influence on the working mode can be reduced.
Preferably, the coupling rings are two coaxial feeding magnetic coupling rings, and the outer conductor of the coaxial is coated with a wave-absorbing material.
Preferably, the coupling ring is spaced apart from the upper and lower plates of the resonator by the same distance.
Preferably, the ring surfaces of the two coupling rings are parallel to the upper and lower resonator plates, and the coupling rings are connected with two ports of the vector network analyzer.
Preferably, the resonator upper plate, and/or the resonator lower plate, are attached to a threaded rod for adjusting the distance between the resonator upper and lower plates. The upper plate and the lower plate of the resonator can be kept parallel by adopting the threads to move stably, and the upper plate and the lower plate of the resonator can be effectively in close contact with a medium to be measured.
Preferably, the diameters of the upper plate and the lower plate of the resonator are 2-5 times of the diameter of the dielectric material to be measured.
Preferably, the upper plate and the lower plate of the resonator are both made of FR-4 hard dielectric substrates with the thickness of 2mm and the diameter of 90 mm.
Preferably, the annular gap has a smallest radius R0Is 1.5mm, the remaining radius extends outward in steps d, Rn＝R0+ nd, n 1,2,3 … …, d 2.5mm, and a gap width of 0.11 mm. The preferable gap width and the gap interval are obtained by comprehensively considering two aspects of energy loss and stray mode suppression based on distribution of the intracavity field and analysis of simulation results of HFSS software. If the gap width is too large or the gap interval is too small, the energy leakage is large, the influence on the working mode is large, and the working mode is also inhibited; if the gap width is too small or the gap interval is too large, the suppression effect on the non-operating mode is not good.
The invention has the beneficial effects that: by adopting the scheme, the invention can cut off the current lines in non-working modes such as TM mode, mixed mode and the like on the premise of ensuring no influence on the working mode or extremely small influence, and cannot generateThe resonance can be generated or weak resonance can be generated only, energy can be radiated out through the gap and is absorbed by the surface of the hard medium substrate coated with the wave-absorbing material, and then most of non-working modes are effectively inhibited, so that the working modes are more easily identified in frequency spectrum, especially in a higher frequency range with more non-working modes, the inhibition effect on the non-working modes is more obvious, and the working modes are clearly visible in the frequency spectrum. Finally, a relatively pure TE can be obtained in a wide range0npA modal spectrum. The method is convenient for finding out the correct working mode more quickly and accurately in the rapid measurement technology, and further improves the measurement speed and accuracy of the complex dielectric constant.
Drawings
Fig. 1 is a diagram of magnetic and electric field lines of a dielectric resonator.
Figure 2 is a top view of the lower plate of the resonator.
Fig. 3 is a schematic diagram of a dielectric resonator of the present invention.
Fig. 4 and 5 are schematic diagrams comparing resonance curves of two dielectric resonators with identical dimensions, materials and processing technologies: fig. 4 is a resonance curve of a conventional dielectric resonator that does not use a hard dielectric substrate with a slit structure, and fig. 5 is a resonance curve of a dielectric resonator that uses the above-described scheme of the present invention and has a hard dielectric substrate with a slit structure on an upper plate and a lower plate of the resonator.
The resonator comprises a resonator upper plate 1, a resonator lower plate 2, a gap structure 3, a dielectric material to be measured 4, a coupling ring 5 and a coupling ring coaxial line part 6.
Detailed Description
A broadband dielectric resonator is shown in figures 2 and 3 and comprises a resonator upper plate 1, a resonator lower plate 2, a dielectric material to be measured 4 and two coupling rings 5, wherein the dielectric material to be measured is arranged between the resonator upper plate and the resonator lower plate, the dielectric material to be measured is pressed by the resonator upper plate and the resonator lower plate, and the resonator upper plate, the resonator lower plate and the dielectric material to be measured form a dielectric resonance part; the upper plate and the lower plate of the resonator are parallel to each other and are made of circular hard dielectric substrates; the dielectric material to be measured is a cylinder which is vertical to the circle centers of the upper plate and the lower plate of the resonator, the two coupling rings are distributed on the two sides of the dielectric material to be measured in opposite directions along the diameter direction of the upper plate and the lower plate of the resonator and point to the circle centers, one surfaces of the upper plate and the lower plate of the resonator, which face the dielectric material to be measured, are provided with metal coating layers, and the other surfaces are coated with wave-absorbing; the metal coating is engraved with a circular gap structure 3, and the gap structure 3 is a circular gap concentric with the upper and lower plates of the resonator.
The thickness of the metal coating is larger than the skin depth of the electromagnetic wave of the working frequency point of the dielectric resonator, and the surface of the metal coating is subjected to gold plating treatment. The surface roughness of the plating layer is better than grade 7.
The gap structure is a plurality of circles of concentric ring gaps uniformly arranged in the radius direction of the circle centers of the upper plate and the lower plate of the resonator, and 5-10 gaps are arranged in the radius range of the dielectric material to be measured.
The coupling rings are two coaxial line feeding magnetic coupling rings, and wave absorbing materials are coated on the outer conductors of the coaxial lines. The coupling rings are equidistant from the upper and lower plates of the resonator. The ring surfaces of the two coupling rings are parallel to the upper plate and the lower plate of the resonator, and the coupling rings are connected with two ports of the vector network analyzer.
The resonator upper plate, and/or the resonator lower plate are attached to a threaded rod (not shown in the drawings) for adjusting the distance between the resonator upper and lower plates. The diameters of the upper plate and the lower plate of the resonator are 2-5 times of the diameter of the dielectric material to be measured.
The upper plate and the lower plate of the resonator are both made of FR-4 hard dielectric substrates with the thickness of 2mm and the diameter of 90 mm.
The radius R0 of the smallest ring is 1.5mm, the remaining radii extend outward in steps d, i.e., Rn — R0+ nd, n — 1,2,3 … …, d — 2.5mm, and the gap width is 0.11 mm.
When the broadband dielectric resonator provided by the invention works, a cylindrical dielectric material to be measured is placed in the center of the dielectric resonator, and the circle center of the cylindrical dielectric material is overlapped with the circle center of the gap as much as possible. After the dielectric material to be tested is placed, the upper plate and the lower plate of the resonator are moved through the threads, so that the upper plate and the lower plate of the resonator are in close contact with the dielectric material to be tested, and the upper plate and the lower plate are ensured to be kept flatThe line state. The position of the coupling ring is adjusted to ensure that the coupling ring is positioned at the strongest position of the magnetic field of the dielectric resonator, and the ring surface is ensured to be vertical to the magnetic force line, so that the distribution disturbance of the field in the cavity is ensured to be small. By selecting the operating mode as TE0npAnd measuring the complex dielectric constant of the dielectric material to be measured by the mode electromagnetic wave. The metal coatings of the upper plate and the lower plate of the dielectric resonator are engraved with a circular ring gap structure concentric with the dielectric material to be measured, so that a great amount of non-TE in the dielectric resonator0npThe electromagnetic wave of the mode cannot form a current loop and cannot generate a resonance phenomenon. But with current loop exactly along the direction of the circle0npThe electromagnetic wave of the mode can form a current loop without interference to generate a resonance phenomenon, thereby realizing that TE is not influenced0npSuppression of non-TE under the premise of mode field distribution0npAnd the resonance of the mode improves the measurement precision of the complex dielectric constant of the dielectric material to be measured. In addition, due to non-TE0npThe current line of the mode is cut off, the electromagnetic wave of the current line leaks out from the gap and is absorbed by the wave-absorbing material coated on the side of the hard dielectric substrate opposite to the dielectric material to be measured, so that the non-TE is further treated0npThe interference of the mode is effectively suppressed, and finally a purer TE is obtained0npAnd the measurement precision of the complex dielectric constant of the dielectric material to be measured is further improved.
Claims (10)
1. A broadband dielectric resonator, comprising: the resonator comprises an upper resonator plate, a lower resonator plate, a dielectric material to be tested and two coupling rings, wherein the dielectric material to be tested is arranged between the upper resonator plate and the lower resonator plate, and is compressed by the upper resonator plate and the lower resonator plate, and the upper resonator plate, the lower resonator plate and the dielectric material to be tested form a dielectric resonance part; the upper plate and the lower plate of the resonator are parallel to each other and are made of circular hard dielectric substrates; the dielectric material to be measured is a cylinder which is vertical to the circle centers of the upper plate and the lower plate of the resonator, the two coupling rings are distributed on the two sides of the dielectric material to be measured in opposite directions along the diameter direction of the upper plate and the lower plate of the resonator and point to the circle centers, one surfaces of the upper plate and the lower plate of the resonator, which face the dielectric material to be measured, are provided with metal coating layers, and the other surfaces are coated with wave-absorbing; the metal coating is carved with circular gap structure, and the gap structure is concentric circular gap with upper and lower plates of the resonator, and the gap structure is a plurality of circles of concentric circular ring gaps uniformly arranged at the center of the upper and lower plates of the resonator along the radius direction.
2. The wideband dielectric resonator of claim 1, wherein: the thickness of the metal coating is larger than the skin depth of the electromagnetic wave of the working frequency point of the dielectric resonator, and the surface of the metal coating is subjected to gold plating treatment.
3. The wideband dielectric resonator of claim 1, wherein: the gap structure is a plurality of circles of concentric ring gaps uniformly arranged in the radius direction of the circle centers of the upper plate and the lower plate of the resonator, and 5-10 gaps are arranged in the radius range of the dielectric material to be measured.
4. The wideband dielectric resonator of claim 1, wherein: the coupling rings are two coaxial line feeding magnetic coupling rings, and wave absorbing materials are coated on the outer conductors of the coaxial lines.
5. The wideband dielectric resonator of claim 1, wherein: the coupling rings are equidistant from the upper and lower plates of the resonator.
6. The wideband dielectric resonator of claim 1, wherein: the ring surfaces of the two coupling rings are parallel to the upper plate and the lower plate of the resonator, and the coupling rings are connected with two ports of the vector network analyzer.
7. The wideband dielectric resonator of claim 1, wherein: the resonator upper plate, and/or the resonator lower plate, are attached to a threaded rod for adjusting the distance between the resonator upper and lower plates.
8. The wideband dielectric resonator of claim 1, wherein: the diameters of the upper plate and the lower plate of the resonator are 2-5 times of the diameter of the dielectric material to be measured.
9. The wideband dielectric resonator of claim 1, wherein: the upper plate and the lower plate of the resonator are both made of FR-4 hard dielectric substrates with the thickness of 2mm and the diameter of 90 mm.
10. A wideband dielectric resonator as claimed in claim 3, wherein: the circle ring gap, wherein the radius R of the smallest circle ring01.5mm, the remaining radii extending outward in steps d, RnIs the radius of the nth circle, Rn＝R0+ nd, n 1,2,3 … …, d 2.5mm, and a gap width of 0.11 mm.
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| CN101325275A (en) * | 2008-06-11 | 2008-12-17 | 电子科技大学 | Multilevel composite resonant cavity for electron cyclotron |
| CN204116459U (en) * | 2014-09-12 | 2015-01-21 | 南京大学 | A kind of dielectric resonator measuring superconducting film material microwave surface impedance |
| RU150609U1 (en) * | 2014-07-29 | 2015-02-20 | Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Санкт-Петербургский государственный электротехнический университет "ЛЭТИ" им. В.И. Ленина | MICROBAND RESONANT MEASURING CELL FOR MEASURING PLANAR CAPACITORS |
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| CN1405569A (en) * | 2001-08-08 | 2003-03-26 | 电子科技大学 | Testing method for complex dielectric permittivity of multi-mould in one chamber, wide-frequency and multi-point microwave medium |
| JP5034692B2 (en) * | 2007-06-04 | 2012-09-26 | オムロン株式会社 | Acoustic sensor |
| CN101079513A (en) * | 2007-06-15 | 2007-11-28 | 杨松涛 | A low-frequency active radiator |
| CN201663219U (en) * | 2010-04-23 | 2010-12-01 | 电子科技大学 | Cylindrical waveguide resonant cavity |
| CN102798766B (en) * | 2012-08-03 | 2014-07-30 | 浙江大学 | Method for testing microwave dielectric property of high-loss dielectric substance |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101325275A (en) * | 2008-06-11 | 2008-12-17 | 电子科技大学 | Multilevel composite resonant cavity for electron cyclotron |
| RU150609U1 (en) * | 2014-07-29 | 2015-02-20 | Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Санкт-Петербургский государственный электротехнический университет "ЛЭТИ" им. В.И. Ленина | MICROBAND RESONANT MEASURING CELL FOR MEASURING PLANAR CAPACITORS |
| CN204116459U (en) * | 2014-09-12 | 2015-01-21 | 南京大学 | A kind of dielectric resonator measuring superconducting film material microwave surface impedance |
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