CN108807113B - Coaxial-like zigzag banded slow wave injection structure - Google Patents

Coaxial-like zigzag banded slow wave injection structure Download PDF

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Publication number
CN108807113B
CN108807113B CN201810414280.9A CN201810414280A CN108807113B CN 108807113 B CN108807113 B CN 108807113B CN 201810414280 A CN201810414280 A CN 201810414280A CN 108807113 B CN108807113 B CN 108807113B
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metal
zigzag
electron beam
slow
waveguide structure
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CN108807113A (en
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许多
师凝洁
王禾欣
何腾龙
李新义
王战亮
宫玉彬
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University of Electronic Science and Technology of China
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University of Electronic Science and Technology of China
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J23/00Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/16Circuit elements, having distributed capacitance and inductance, structurally associated with the tube and interacting with the discharge
    • H01J23/24Slow-wave structures, e.g. delay systems
    • H01J23/26Helical slow-wave structures; Adjustment therefor

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Abstract

The invention discloses a coaxial zigzag banded slow wave injection structure, which comprises a metal shell, a metal slow wave line and two medium supporting rods, wherein the metal shell is divided into an inner layer and an outer layer, the inner layer adopts a zigzag waveguide structure, an electron beam channel is banded, and a bending part between two adjacent ridge sheets of the zigzag waveguide structure is provided with an opening; the metal slow wave line is obtained by folding a metal wire, the folding path is the same as that of the zigzag waveguide structure of the inner layer of the metal shell, and the same electron beam channel is arranged; two medium supporting rods are respectively fixed between the inner layer and the outer layer of the two sides of the metal shell, part of the side surfaces of the medium supporting rods are exposed out of an opening formed in the zigzag waveguide structure and are in surface contact with the slow metal wave line, and the slow metal wave line is clamped and suspended in the inner cavity of the metal shell. The invention can reduce the dispersion characteristic and improve the coupling impedance on the premise of ensuring large bandwidth.

Description

Coaxial-like zigzag banded slow wave injection structure
Technical Field
The invention belongs to the technical field of ribbon beam traveling wave tube slow wave systems, and particularly relates to a coaxial-like zigzag ribbon beam slow wave structure.
Background
The traveling wave tube has a very wide application field as a microwave power device, and has different characteristics for different application modes, generally speaking, the traveling wave tube has advantages of wide frequency band, high power, high gain, high efficiency, high gain, long service life and the like.
The slow-wave structure is a device for enhancing the interaction between moving electrons and an electromagnetic field in a traveling wave type electronic device, and converting the energy of electron current into high-frequency energy of electromagnetic waves more effectively. The slow wave structure is used as the core part of the traveling wave tube, and the quality of the slow wave structure directly determines the quality of the technical level of the traveling wave tube.
The traditional plane slow wave structure comprises a micro-strip slow wave structure and a strip slow wave structure, wherein the electric field energy of the micro-strip slow wave structure is mainly concentrated in a medium substrate of the micro-strip slow wave structure, and the electric field energy is more obvious along with the reduction of the thickness of the medium substrate and the increase of the dielectric constant of the medium substrate, and the defects of poor transmission characteristic, narrow bandwidth and the like exist; the chromatic dispersion of the banded slow-wave structure has larger correlation with more structural parameters, and the chromatic dispersion is generally stronger under the limitation of the existing processing conditions.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a similar coaxial zigzag banded slow wave injection structure, wherein the inner layer of a metal shell and a metal slow wave line adopt structures similar to a zigzag folded coaxial line, and two medium supporting rods are adopted to support the metal slow wave line, so that the dispersion characteristic can be reduced, and the coupling impedance is improved on the premise of ensuring a large bandwidth.
In order to achieve the purpose, the coaxial zigzag banded slow wave injection structure comprises a metal shell, a metal slow wave line and two medium supporting rods, wherein:
the metal shell is divided into an inner layer and an outer layer, the inner layer adopts a zigzag waveguide structure, a strip-shaped electron beam channel is arranged on the upper and lower symmetrical planes of the zigzag waveguide structure, the section of the electron beam channel completely comprises an electron beam section, and an opening is arranged at the bending position between two adjacent ridge sheets of the zigzag waveguide structure;
the metal slow wave line is obtained by folding a metal wire, the folding path is the same as that of the zigzag waveguide structure of the inner layer of the metal shell, holes are punched on the upper and lower symmetrical surfaces of the folded metal wire to form an electron beam channel, and the electron beam channel is superposed with the electron beam channel of the zigzag waveguide structure of the inner layer of the metal shell;
two medium supporting rods are respectively fixed between the inner layer and the outer layer of the two sides of the metal shell, part of the side surfaces of the medium supporting rods are exposed out of an opening formed in the zigzag waveguide structure and are in surface contact with the slow metal wave line, and the slow metal wave line is clamped and suspended in the inner cavity of the metal shell.
The invention relates to a quasi-coaxial zigzag banded slow wave injection structure, which comprises a metal shell, a metal slow wave line and two medium supporting rods, wherein the metal shell is divided into an inner layer and an outer layer, the inner layer adopts a zigzag waveguide structure, an electron beam channel is banded, and a bending part between two adjacent ridge sheets of the zigzag waveguide structure is provided with an opening; the metal slow wave line is obtained by folding a metal wire, the folding path is the same as that of the zigzag waveguide structure of the inner layer of the metal shell, and the same electron beam channel is arranged; two medium supporting rods are respectively fixed between the inner layer and the outer layer of the two sides of the metal shell, part of the side surfaces of the medium supporting rods are exposed out of an opening formed in the zigzag waveguide structure and are in surface contact with the slow metal wave line, and the slow metal wave line is clamped and suspended in the inner cavity of the metal shell. The invention can reduce the dispersion characteristic and improve the coupling impedance on the premise of ensuring large bandwidth.
Drawings
FIG. 1 is a block diagram of an embodiment of a quasi-coaxial meandering ribbon beam slow wave structure of the present invention;
FIG. 2 is an enlarged view of the lower half of the structure of the quasi-coaxial meandering band-shaped beam slow wave structure shown in FIG. 1;
FIG. 3 is a single-cycle structure diagram of a quasi-coaxial meandering ribbon-like slow-wave structure shown in FIG. 1;
FIG. 4 is a schematic view of a meandering waveguide structure;
FIG. 5 is a transverse cross-sectional view of a quasi-coaxial meandering, ribbon-like beam slow wave structure shown in FIG. 1;
FIG. 6 is a longitudinal cross-sectional view of a quasi-coaxial meandering, ribbon-like beam slow wave structure shown in FIG. 1;
fig. 7 is a result of transmission characteristic simulation of the present embodiment;
fig. 8 is a result of the normalized phase velocity simulation of the present embodiment.
Detailed Description
The following description of the embodiments of the present invention is provided in order to better understand the present invention for those skilled in the art with reference to the accompanying drawings. It is to be expressly noted that in the following description, a detailed description of known functions and designs will be omitted when it may obscure the subject matter of the present invention.
Examples
FIG. 1 is a structural diagram of an embodiment of a coaxial meandering strip-shaped beam slow wave structure of the present invention. In order to show the internal structure of the ultra-wideband planar dual-beam slow-wave structure more clearly, in fig. 1, the quasi-coaxial zigzag strip-shaped beam slow-wave structure is divided by taking the plane of the electron beam as a cross section to obtain an upper half part and a lower half part. Fig. 2 is an enlarged view of the lower half structure of the quasi-coaxial meandering band-shaped beam slow wave structure shown in fig. 1. As shown in fig. 1 and fig. 2, the coaxial zigzag band-shaped slow wave injection structure of the present invention includes a metal casing 1, a metal slow wave line 2 and two medium support rods 3. As in the conventional slow wave structure, an electron entrance port 4, a signal entrance port 5, and a signal exit port 6 of an electron gun are added at appropriate positions as required.
Fig. 3 is a single-cycle structure diagram of the quasi-coaxial meandering strip-shaped beam slow wave structure shown in fig. 1. As shown in fig. 3, the metal shell 1 of the present invention is divided into an inner layer 11 and an outer layer 12, and the inner layer 11 adopts a zigzag waveguide structure. Fig. 4 is a schematic view of a meandering waveguide structure. As shown in fig. 4, the zigzag waveguide is periodically bent like a zigzag line along the electric field plane, and holes are formed through the metal wall from top to bottom along the symmetry axis of the slow-wave structure, so as to form electron beam channels. The meander waveguide is a common structure in the field of traveling wave tubes, and the detailed principle and structure thereof are not described herein. In order to achieve the object of the present invention, it is necessary to improve the conventional meandering waveguide: and a strip-shaped electron beam channel is arranged on the upper and lower symmetrical planes of the zigzag waveguide structure, the section of the electron beam channel completely comprises an electron beam section, and an opening is arranged at the bending position between two adjacent ridge sheets of the zigzag waveguide structure. In this embodiment, each curve of each bend in the zigzag waveguide structure is composed of two quarter arcs and a straight line segment connecting the two quarter arcs. When the improvement in detail occurs in the zigzag waveguide structure, the folding path thereof naturally changes accordingly. The specific shape of the electron beam channel cross section can be adjusted according to actual needs, and a rectangle is adopted in the embodiment.
Fig. 5 is a transverse cross-sectional view of a quasi-coaxial meandering bandlike slow wave structure shown in fig. 1. As shown in fig. 3 and 5, the slow wave metal wire 2 is obtained by folding a metal wire, the folding path is the same as that of the zigzag waveguide structure of the inner layer 11 of the metal shell 1, holes are punched on the upper and lower symmetrical surfaces of the folded metal wire to form an electron beam channel, and the electron beam channel is overlapped with the electron beam channel of the zigzag waveguide structure of the inner layer of the metal shell, i.e. an electron beam channel 7 is formed. In FIG. 5, w represents the thickness of the metal line of the metal slow wave line 2, w2The length of a straight line segment at a bending position in the zigzag waveguide structure in the embodiment is shown, p is the length of a single period of the metal line periodic structure, and w iseDenotes the width, w, of the electron beam pathcIndicates the width of the electron beam, obviously we>wc,wdThe width of the dielectric support rods is shown and L represents the length of the straight line segments in the ridge in the meandering waveguide structure.
As shown in fig. 3 and 5, two dielectric support rods 3 are respectively fixed between an inner layer 11 and an outer layer 12 on both sides of the metal shell 1, and part of the side surfaces of the dielectric support rods are exposed from an opening arranged on the zigzag waveguide structure of the inner layer 11 and are in surface contact with the metal slow wave line 2, so that the metal slow wave line 2 is clamped and suspended in the inner cavity of the metal shell 1. In the invention, the metal slow wave line 2 is embedded in the inner cavity of the metal shell 1. The specific shape of the medium supporting rod 3 can be set according to actual needs, and a straight quadrangular prism with a rectangular cross section is adopted in the embodiment.
Fig. 6 is a longitudinal cross-sectional view of a quasi-coaxial meandering ribbon-like slow wave structure shown in fig. 1. In FIG. 6, w represents the thickness of the metal line of the metal slow wave line 2, a represents the height of the inner layer 11 of the metal shell 1, t represents the thickness of the metal line, t representseDenotes the thickness of the electron beam path, tcDenotes the thickness of the electron beam, apparently te>tc,tdThe thickness of the media support bar is shown. As shown in fig. 6, the electron beam channel in the present invention runs through the meander waveguide structure and the metal slow wave line.
As can be seen from the foregoing description of the present invention, the coaxial zigzag banded slow-wave-injection structure of the present invention can be regarded as that after a coaxial line is folded, two dielectric support rods are embedded in the metal shells at two sides of the coaxial line shell (i.e. the inner layer 11 of the metal shell 1) where there is a bend, so as to support the coaxial inner core (i.e. the metal slow-wave line 2) to be suspended and insulated from the metal shells. Obviously, in the above structure, the folded coaxial outer shell and inner core may have an overlapping area with the electron beam passage. Therefore, the present invention is substantially the structure left after the non-vacuum area overlapped with the electron beam channel is removed from the folded coaxial line (including the dielectric support rod), and therefore the present invention is called as a quasi-coaxial zigzag band-shaped beam slow wave structure.
The invention adopts a folding structure similar to a coaxial line and clamps the metal slow wave line on two sides through the medium supporting rod, so that the metal slow wave line is insulated from the metal shell, and the double-line transmission line is formed. The fundamental mode in the coaxial line is a TEM mode, and due to the similarity of the structure of the coaxial line and the structure of the coaxial line, the fundamental mode has similarity with the TEM mode, and can be qualitatively analyzed into a QTEM mode. The phase speed of the fundamental mode can be determined according to the phase speed of the QTEM mode electromagnetic wave transmitted along the metal wire and the period parameter of the periodic structure, and under the condition of determining the period parameter of the periodic structure, the dispersion characteristic of the slow wave structure is uniquely determined by the dispersion characteristic of the QTEM mode electromagnetic wave transmitted along the metal wire, and the QTEM mode has the weak dispersion characteristic, so that the wide working bandwidth can be realized.
The mode of the electromagnetic wave transmitted along the metal slow wave line is a QTEM mode, the mode has higher similarity with a TEM mode in a uniform coaxial line, and for convenience of analysis, a TEM mode electric field in the coaxial line can be used for replacing the QTEM mode electric field to carry out approximate analysis. In the uniform circular coaxial line, the direction of the electric field is directed to the coaxial shell from the coaxial inner core, the size of the electric field is reduced along with the increase of the distance from the field position to the coaxial inner core, and the electron beam channel passes through the inner core, so the field intensity of the electron beam channel is strongest, and the longitudinal component of the electric field is the largest.
In addition, the conventional broadband microstrip type slow-wave structure generally has the problem of low coupling impedance, and the main reason is that the dielectric material occupies too large proportion in the cavity, so that electric field energy is concentrated to an area where wave injection interaction cannot be performed, and therefore, the electric field of an electron beam path area is small, and the coupling impedance of the area can be known to be low according to the definition of the coupling impedance. Compared with the traditional microstrip type slow wave structure, the microstrip type slow wave structure adopts the medium supporting rods on the two sides to clamp the metal slow wave lines, reduces the space proportion of the dielectric medium in the metal cavity of the slow wave structure, and weakens the tendency of concentrating electric field energy into the dielectric medium, thereby realizing higher coupling impedance.
In order to better illustrate the technical effects of the invention, the invention is subjected to simulation verification. Fig. 7 is a result of transmission characteristic simulation of the present embodiment. In fig. 7, S11 represents the input reflection coefficient, i.e., the input return loss, and S21 represents the forward transmission coefficient, i.e., the gain. As shown in fig. 7, in a wide frequency range of 60GHz or less, the transmission coefficient of the present embodiment is lower than-17 dB, and the transmission characteristics are good.
Fig. 8 is a result of the normalized phase velocity simulation of the present embodiment. The normalized phase velocity is used to characterize the dispersion of the slow wave structure. As shown in fig. 8, in the frequency range below 60GHz, the normalized phase velocity variation of the electromagnetic waves of different frequencies transmitted in the present embodiment is small, and the combination with the results of fig. 7 can show that the present invention has a large bandwidth.
Although illustrative embodiments of the present invention have been described above to facilitate the understanding of the present invention by those skilled in the art, it should be understood that the present invention is not limited to the scope of the embodiments, and various changes may be made apparent to those skilled in the art as long as they are within the spirit and scope of the present invention as defined and defined by the appended claims, and all matters of the invention which utilize the inventive concepts are protected.

Claims (4)

1. The utility model provides a coaxial zigzag banding slow wave structure of annotating which characterized in that, includes metal casing, metal slow wave line and two medium bracing pieces, wherein:
the metal shell is divided into an inner layer and an outer layer, the inner layer adopts a zigzag waveguide structure, a strip-shaped electron beam channel is arranged on the upper and lower symmetrical planes of the zigzag waveguide structure, the section of the electron beam channel completely comprises an electron beam section, and an opening is arranged at the bending part between two adjacent ridge sheets of the zigzag waveguide structure;
the metal slow wave line is obtained by folding a metal wire, the folding path is the same as that of the zigzag waveguide structure of the inner layer of the metal shell, holes are punched on the upper and lower symmetrical surfaces of the folded metal wire to form an electron beam channel, and the electron beam channel is superposed with the electron beam channel of the zigzag waveguide structure of the inner layer of the metal shell;
the two medium supporting rods are respectively fixed between the inner layer and the outer layer of the two sides of the metal shell, part of the side surfaces of the medium supporting rods are exposed out of an opening formed in the zigzag waveguide structure and are in surface contact with the slow metal wave line, and the slow metal wave line is clamped, so that the slow metal wave line is suspended in the inner cavity of the metal shell.
2. The structure of claim 1, wherein the curve of each bend in the meandering waveguide structure is composed of two quarter arcs and a straight line segment connecting the two quarter arcs.
3. The structure of claim 1, wherein the electron beam channel has a rectangular cross section.
4. The structure of claim 1, wherein the dielectric support rods are rectangular prisms with rectangular cross sections.
CN201810414280.9A 2018-05-03 2018-05-03 Coaxial-like zigzag banded slow wave injection structure Expired - Fee Related CN108807113B (en)

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CN109904049B (en) * 2019-03-22 2020-12-01 电子科技大学 Symmetrical ridge loading conformal micro-strip zigzag line slow wave device
CN110473756B (en) * 2019-09-12 2021-03-30 电子科技大学 Plane integratable slow wave structure and manufacturing method thereof
CN111017865B (en) * 2019-11-27 2022-09-09 上海交通大学 Preparation method for terahertz folded waveguide microstructure
CN114203502B (en) * 2021-12-03 2023-03-14 电子科技大学 Ridge-loading rhombic meander line slow wave structure based on multiple medium rods
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US5332947A (en) * 1992-05-13 1994-07-26 Litton Systems, Inc. Integral polepiece RF amplification tube for millimeter wave frequencies
JPH0927279A (en) * 1995-07-12 1997-01-28 Nec Corp Traveling wave tube
CN101572205A (en) * 2009-06-10 2009-11-04 电子科技大学 Zigzag slow-wave line of double ridged waveguide
CN101615553A (en) * 2009-07-22 2009-12-30 电子科技大学 A kind of rectangular-grooved loading winding waveguide slow wave line
CN106340433A (en) * 2016-10-18 2017-01-18 电子科技大学 High-frequency structure for dielectric-embedded zigzag metal band
CN107180734A (en) * 2017-06-13 2017-09-19 电子科技大学 The angular tortuous slow wave line slow-wave structure of clamping biradial beam angle logarithm plane
CN107833815A (en) * 2017-10-30 2018-03-23 电子科技大学 A kind of tortuous banding slow wave system of Plane Angle logarithm

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5332947A (en) * 1992-05-13 1994-07-26 Litton Systems, Inc. Integral polepiece RF amplification tube for millimeter wave frequencies
JPH0927279A (en) * 1995-07-12 1997-01-28 Nec Corp Traveling wave tube
CN101572205A (en) * 2009-06-10 2009-11-04 电子科技大学 Zigzag slow-wave line of double ridged waveguide
CN101615553A (en) * 2009-07-22 2009-12-30 电子科技大学 A kind of rectangular-grooved loading winding waveguide slow wave line
CN106340433A (en) * 2016-10-18 2017-01-18 电子科技大学 High-frequency structure for dielectric-embedded zigzag metal band
CN107180734A (en) * 2017-06-13 2017-09-19 电子科技大学 The angular tortuous slow wave line slow-wave structure of clamping biradial beam angle logarithm plane
CN107833815A (en) * 2017-10-30 2018-03-23 电子科技大学 A kind of tortuous banding slow wave system of Plane Angle logarithm

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