CN110299584A - A kind of overmoded waveguide filter suitable for high-power millimeter wave transmission line - Google Patents
A kind of overmoded waveguide filter suitable for high-power millimeter wave transmission line Download PDFInfo
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- CN110299584A CN110299584A CN201910603227.8A CN201910603227A CN110299584A CN 110299584 A CN110299584 A CN 110299584A CN 201910603227 A CN201910603227 A CN 201910603227A CN 110299584 A CN110299584 A CN 110299584A
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/16—Auxiliary devices for mode selection, e.g. mode suppression or mode promotion; for mode conversion
- H01P1/163—Auxiliary devices for mode selection, e.g. mode suppression or mode promotion; for mode conversion specifically adapted for selection or promotion of the TE01 circular-electric mode
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/20—Frequency-selective devices, e.g. filters
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Abstract
The invention discloses a kind of overmoded waveguide filters suitable for high-power millimeter wave transmission line, belong to high-power millimeter wave transmission technique field.The filter includes input, exported mould circular waveguide, and irradiation structure inhales wave apparatus and support construction；Inputting, exporting mould circular waveguide is the uniform circular waveguide for being symmetrically disposed on irradiation structure two sides, irradiation structure is the Circular waveguides for being provided with period-interleaving radiating slot unit, the axially disposed radiating slot ring for thering is the period to arrange of the Circular waveguides, one radiating slot ring is divided into 4 identical radiating slot units by interband connection structure, and the interband connection structure of adjacent two radiating slots ring, which is interlocked 45 °, to be arranged.Overmoded waveguide filter construction of the invention is compact, and power capacity is big, and can be in broad frequency range to asymmetric mode TE11Mould, TE11Mould, TE21Mould, TM11Mould, TE31Mould realizes efficient filtering, without influencing TE01The propagation of the symmetric patterns such as mould, it is applied widely.
Description
Technical Field
The invention belongs to the technical field of high-power millimeter wave transmission, and particularly relates to a high-power millimeter wave over-mode waveguide filter for filtering a non-annular waveguide mode.
Background
The gyrotron traveling wave tube is a broadband power source which can only realize high-power output in a millimeter wave band. The high-gain broadband microwave imaging radar has the characteristics of high gain, broadband, high power and the like, and has very wide application prospects in the fields of imaging radars, millimeter wave communication systems, electronic countermeasures, microwave weapons and the like. Circular waveguide TE01The mode is a common working mode of the gyrotron traveling wave tube, and because the mode is distributed in a ring shape, energy is concentrated in the center of the waveguide, a fringe field is weak, and transmission loss is low compared with other modes. Thus, the circular waveguide TE01The mode is a common working mode of a gyrotron traveling wave tube and is also a common transmission mode of a high-power millimeter wave transmission link. In order to avoid power breakdown and reduce transmission loss, an overmoded circular waveguide structure is adopted for a high-power transmission line for realizing butt joint of the gyrotron traveling wave tube and the antenna. Compared with a single-mode waveguide transmission line, the over-mode waveguide transmission line is easy to excite a parasitic mode, and the transmission performance is reduced. For example, to achieve beam steering, a bevel bend or a continuously varying over-mode waveguide bend is placed on the transmission line. TE resulting from the use of these over-mode waveguide bends11Mode, TM11Mold, TE21Mode, etc. parasitic mode generation. In addition, even in a uniform circular waveguide, TE is caused by waveguide tilt, twist, misalignment, and the like introduced by mounting and processing11Mode, TM11Mold, TE21Generation of modes such as modulo etc. And operating mode TE01The modes differ in that these parasitic modes have strong fringing fields at the waveguide walls and the presence of these parasitic modes can have a series of undesirable effects on the system. For TE11Mode, TM11Mold, TE21In terms of modes such as mode, during the process of forward propagation along the high-power transmission line, the local field intensity is enhanced due to the phase change, so that the system is easy to break down and cannot break downAnd (5) stable operation. Meanwhile, when air breakdown occurs, total reflection is formed, and high-power electromagnetic waves are totally reflected back to the power source, so that the power source is easily damaged. In addition, due to the characteristic of the edge field intensity, the non-working modes can cause breakdown of high-power rotary joints based on a slit structure and a corrugated groove structure, mode conversion and the like, so that the normal operation of the system is influenced. In order to ensure the stable operation of the high-power millimeter wave system, TE must be filtered11Mode, TM11Mold, TE21And a mode and the like are non-working modes.
Therefore, the development of a high-performance over-mode waveguide filter is particularly necessary for establishing a stable high-power millimeter wave application system. Currently, the commonly used mode filters mainly have an impedance wall type and a corrugated groove type. Impedance wall mode filters, proposed by w.d. starters ("The effect of mode filters on The transmission characteristics of circular electric waves in a circular wave guide," bell.syst.tech.j., vol.37, pp.657-677,1958 "), achieve The filtering effect by embedding a specific shape of attenuating ceramic in The waveguide to absorb a specific mode. However, embedding a dielectric slab in a waveguide has significant process difficulties. Meanwhile, when the waveguide is applied to a high-power system, the medium fins embedded in the waveguide are difficult to dissipate heat. Silvia Ceccuzzi and Cristina Ponti et al designed a corrugated notch Mode filter ("model Filters for inverted filtered Waveguides: AModoral Approach", IEEE trans. on micro. the same and tech., VOL.63, NO.8, August 2015). The filter filters parasitic modes by slotting the inner surface of the waveguide and embedding media, and has good filtering performance. Compared with an impedance wall, the corrugated groove type structure is easier to dissipate heat, but the processing difficulty is still higher, and the cost of the filter is higher due to the use of a large number of media.
Disclosure of Invention
The invention provides a technical scheme of a high-power millimeter wave circular waveguide asymmetric mode filter, aiming at the problems of complex design structure, difficulty in implementation, high processing cost and the like in the prior art.
The technical scheme adopted by the invention is as follows:
an over-mode waveguide filter suitable for a high-power millimeter wave transmission line comprises an input over-mode circular waveguide, an output over-mode circular waveguide, a radiation structure with filtering performance, a wave absorbing device and a supporting structure.
The input and output overmoded circular waveguides are uniform circular waveguides with the same caliber and are symmetrically arranged at two ends of the radiation structure, and waveguide flanges are arranged on the outer sides of the input and output overmoded circular waveguides to realize connection with a high-power transmission line.
The radiation structure is a circular waveguide structure provided with periodically staggered radiation gap units, the circular waveguide structure is provided with periodically arranged radiation gap rings along the axial direction, one radiation gap ring is divided into 4 same radiation gap units by 4 interband connecting structures, and the interband connecting structures of two adjacent radiation gap rings are arranged in a staggered way by 45 degrees.
To be in a guarantee operating mode TE01The parasitic modes are filtered out as much as possible while the modes are transmitted efficiently, the width of the radiation slit unit in the longitudinal direction is not more than lambda/4, and the interval between adjacent radiation slit rings in the longitudinal direction is not more than lambda/3. Wherein λ is the wavelength corresponding to the working center frequency of the filter. By increasing or decreasing the width of the radiating slot element, different filtering effects on parasitic modes can be obtained.
Further, the cross section of the inter-belt connecting structure is of a fan-shaped structure. The inter-band connecting structure plays a supporting role, structural deformation caused by hollow waveguide walls is prevented, and the width of the inter-band connecting structure in the angular direction is larger than 3 degrees.
The wave absorbing device is positioned outside the radiation structure and can efficiently absorb the non-working mode of the link radiated from the radiation gap unit. In order to avoid overhigh local documents under the condition of high power, the wave absorbing device is provided with a heat radiating device in a matching way. The wave absorbing device material can be high-loss ceramic, wave absorbing sponge or water pipe.
The supporting structure is supporting rods which are uniformly distributed on the outer side of the wave absorbing device and connected with waveguide flanges at two ends. The supporting structure can effectively enhance the mechanical strength and prevent the filter from deforming.
The working principle of the over-mode waveguide mode filter is as follows:
in circular waveguides, the working mode TE01Die and TE11、TE21、TM11、TE31There is a large difference in the field distribution of the equal parasitic modes. From the electromagnetic wave theory, the waveguide surface current J can be represented by the formula
And (4) pushing out. Wherein,normal vector of surface, H1And H2Representing two different magnetic fields. For TEnmThe mode of the operation is set to be,
for TMnmThe mode of the operation is set to be,
wherein HZ、HρAndrepresenting axial, radial and azimuthal magnetic fields, respectively, A and B being amplitude constants, JnIs a Bessel function of the first kind, p represents the radius of a circular waveguide, β is the propagation constant of the mode, kcThe cut-off wavenumber.
Can be pushed out, TE01The mode has only circumferential surface current and no surface current distribution in the axial direction. And TE11、TE21、TM11、TE31Equal parasitic modes, there is an axially distributed surface current. Therefore, the arrangement of the strip-shaped radiation slit unit can not affect the TE01Efficient cut-off of TE while transferring in mode11、TE21、TM11、TE31Etc. of the parasitic mode. For TE01The strip-shaped radiating slot elements are weak in terms of modeThe radiation gap does not affect the transmission; for the parasitic mode, the strip-shaped radiation slit unit is a strong radiation slit, and the parasitic mode will radiate outwards through the strip-shaped radiation slit unit and be absorbed by the absorption device at the outer side. After the mixed wave beam on the high-power transmission link enters the waveguide mode filter through the input end, the non-working mode realizes effective filtering through the radiation structure. Therefore, only the working mode can effectively pass through the filter, and the purification of the high-power millimeter wave beam is realized.
The invention has the following advantages:
1. the filter adopts a waveguide structure based on an overmode, has large power capacity, and can carry out TE on an asymmetric mode in a wide frequency band range11Mold, TE11Mold, TE21Mode, TM11Mold, TE31Modulo implementation efficient filtering without affecting TE01The propagation of symmetric modes such as mode and the like, and the application range is wide.
2. The over-mode waveguide filter has compact structure, has less influence on the layout of a high-power transmission line, and is beneficial to the integration of a system.
3. The over-mode waveguide filter can filter mode indexes, flexibly adjust the length of a radiation structure and has strong universality.
4. The radiation structure of the over-mode waveguide filter is an all-metal structure, only the circular waveguide needs to be hollowed out, and the over-mode waveguide filter is simple in structure, low in cost, easy to process and convenient to assemble.
Drawings
FIG. 1 is a schematic structural diagram of an embodiment of the invention without a wave-absorbing device.
Fig. 2 is a schematic view of a radiation structure of an embodiment of the present invention.
Fig. 3 is a schematic structural diagram of a wave absorbing device in the embodiment of the invention.
FIG. 4 is a reflection graph of an embodiment of the present invention.
Fig. 5 is a transmission graph of an embodiment of the present invention.
The reference numbers illustrate: the microwave-assisted wave absorption device comprises an input/output overmoded circular waveguide 1, a radiation structure 2, a waveguide flange 3, a support structure 4, a radiation gap unit 5, an interband connection structure 6 and a wave absorption device 7.
Detailed Description
The following describes a specific embodiment of the present invention by taking a Ka-band all-metal high-power millimeter wave asymmetric-mode filter as an example, with reference to the accompanying drawings.
As shown in fig. 1 and fig. 2, an overmoded waveguide filter suitable for a high-power millimeter wave transmission line comprises an input/output overmoded circular waveguide 1 and a radiation structure 2 with a filtering performance.
The input and output overmoded circular waveguides 1 are uniform circular waveguides with the same caliber and the same structure, and are symmetrically arranged at two ends of the radiation structure, and in the embodiment, the inner radius R of the input and output overmoded circular waveguides 1 is 16 mm. And concave-convex flanges 3 are arranged on the outer sides of the input and output overmoded circular waveguides to realize the connection with a high-power transmission line.
The radiation structure is a circular waveguide structure provided with periodically staggered radiation gap units, the circular waveguide structure is provided with periodically arranged radiation gap rings along the axial direction, one radiation gap ring is divided into 4 same radiation gap units by 4 interband connecting structures, and the interband connecting structures of two adjacent radiation gap rings are arranged in a staggered way by 45 degrees.
To be in a guarantee operating mode TE01While the mode is transmitted efficiently, parasitic modes are filtered as much as possible, the width of the radiation slit unit 5 in the longitudinal direction is not more than lambda/4, and the interval between adjacent radiation slit rings in the longitudinal direction is not more than lambda/3. Wherein λ is the wavelength corresponding to the working center frequency of the filter. In this embodiment, the width of the radiation slit unit in the longitudinal direction is 1.7mm, and the interval between adjacent radiation slit rings in the longitudinal direction is 1.9 mm.
The cross section of the interband connecting structure 6 is of a fan-shaped structure, so that the interband connecting structure plays a supporting role, structural deformation caused by hollow waveguide walls is prevented, and the width of the interband connecting structure in the angular direction is larger than 3 degrees. In the present embodiment, the width of the inter-belt connecting structure 6 in the angular direction is 5 °.
The wave absorbing device 7 is a water pipe and surrounds the outer side of the radiation structure 2, and can efficiently absorb filtered miscellaneous modes radiated out of the link through the radiation structure 2.
The supporting structures 4 are supporting rods made of high-strength plastics, are uniformly distributed on the outer side of the wave absorbing device 7 and are connected and fixed with the waveguide flanges 3 at two ends. The supporting structure can effectively enhance the mechanical strength and prevent the filter from deforming.
By comprehensively considering the filtering effect and the size of the device, the radiation structure of the present embodiment adopts 40 periodic radiation slit rings.
Fig. 4 and 5 show S-parameter curves of the present embodiment. In the figure, TE01 mode is the working mode, TE11、TE21、TM11、TE31For the representation of the asymmetric parasitic mode, a reflection curve (S) is plotted11) And a transmission curve (S)21). It can be seen that all modes have very small reflection coefficients, below-20 dB. Meanwhile, the asymmetric parasitic mode is effectively attenuated, and the transmission coefficient of the asymmetric parasitic mode is lower than-10 dB in a frequency band of 26GHz-31 GHz; operating mode TE01The modes are hardly affected and their transmission coefficient is approximately equal to 0 dB.
In conclusion, the all-metal high-power millimeter wave of the embodiment can be used without affecting the operation mode TE01Under the condition of mode transmission, the asymmetric parasitic mode is effectively filtered, and the filter has excellent performance.
The above examples are merely for convenience of illustration, and the present invention is also applicable to asymmetric mode filters of other frequency bands, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof and are intended to be included in the scope of the present invention.
Claims (6)
1. The multimode waveguide filter suitable for the high-power millimeter wave transmission line comprises an input multimode circular waveguide, an output multimode circular waveguide and a radiation structure, and is characterized in that the input and output multimode circular waveguides are uniform circular waveguides with the same caliber and are symmetrically arranged at two ends of the radiation structure, and waveguide flanges are arranged on the outer sides of the input and output multimode circular waveguides to realize connection with the high-power transmission line;
the radiation structure is a circular waveguide structure provided with periodically staggered radiation gap units, the circular waveguide structure is provided with periodically arranged radiation gap rings along the axial direction, one radiation gap ring is divided into 4 same radiation gap units by 4 interband connecting structures, and the interband connecting structures of two adjacent radiation gap rings are arranged in a staggered way by 45 degrees.
2. The over-mode waveguide filter suitable for high-power millimeter wave transmission lines as claimed in claim 1, wherein the width of said radiating slot elements in the longitudinal direction is not more than λ/4, and the interval between adjacent radiating slot rings in the longitudinal direction is not more than λ/3, where λ is the wavelength corresponding to the operating center frequency of the filter.
3. The over-mode waveguide filter suitable for high-power millimeter wave transmission lines as claimed in claim 1, wherein said inter-band connection structure has a fan-shaped cross section with a width greater than 3 ° in the angular direction.
4. The multimode waveguide filter of claim 1, further comprising a wave absorbing means and a heat dissipating means located outside the radiating structure.
5. The over-mode waveguide filter suitable for high-power millimeter wave transmission lines of claim 4, wherein the wave-absorbing device is made of high-loss ceramics, wave-absorbing sponge or water pipe.
6. The over-mode waveguide filter suitable for high-power millimeter wave transmission lines as claimed in claim 4, further comprising support rods uniformly distributed outside the wave absorbing device, wherein the support rods are connected to waveguide flanges at two ends.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201910603227.8A CN110299584A (en) | 2019-07-05 | 2019-07-05 | A kind of overmoded waveguide filter suitable for high-power millimeter wave transmission line |
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| CN201910603227.8A CN110299584A (en) | 2019-07-05 | 2019-07-05 | A kind of overmoded waveguide filter suitable for high-power millimeter wave transmission line |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114497947A (en) * | 2022-01-24 | 2022-05-13 | 南通大学 | Double-slit mode selection type transmission line |
| CN114725638A (en) * | 2022-04-26 | 2022-07-08 | 电子科技大学 | High-power water load device based on conical parabolic reflecting surface |
-
2019
- 2019-07-05 CN CN201910603227.8A patent/CN110299584A/en active Pending
Non-Patent Citations (1)
| Title |
|---|
| MINXING WANG等: "Design of a Ka-band High Power Oversized Waveguide Mode Filter"", 《2019 INTERNATIONAL VACUUM ELECTRONICS CONFERENCE (IVEC)》 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114497947A (en) * | 2022-01-24 | 2022-05-13 | 南通大学 | Double-slit mode selection type transmission line |
| CN114497947B (en) * | 2022-01-24 | 2023-03-10 | 南通大学 | Double-slit mode selection type transmission line |
| CN114725638A (en) * | 2022-04-26 | 2022-07-08 | 电子科技大学 | High-power water load device based on conical parabolic reflecting surface |
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Application publication date: 20191001 |