CN112466731A - Microstrip meander line slow wave structure - Google Patents
Microstrip meander line slow wave structure Download PDFInfo
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- CN112466731A CN112466731A CN202011339480.6A CN202011339480A CN112466731A CN 112466731 A CN112466731 A CN 112466731A CN 202011339480 A CN202011339480 A CN 202011339480A CN 112466731 A CN112466731 A CN 112466731A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
- H01J23/16—Circuit elements, having distributed capacitance and inductance, structurally associated with the tube and interacting with the discharge
- H01J23/24—Slow-wave structures, e.g. delay systems
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Abstract
The invention discloses a microstrip meander line slow wave structure, belonging to the field of vacuum electronics, comprising: a microstrip meander line structure; the microstrip zigzag line structure comprises a medium substrate and a metal patch layer positioned on the medium substrate, wherein the metal patch layer is formed by alternately arranging U-shaped metal wires and rectangular metal wires. Through the modification design of the microstrip metal wire and the optimized design of the transition waveguide and the microstrip probe, better transmission characteristics are obtained. Meanwhile, the microstrip zigzag slow wave structure provided by the invention has the advantages of simple structure, small size and the like, is suitable for technical processing of printed circuit boards, and can reduce the volume of a traveling wave tube, reduce the processing cost of the traveling wave tube and improve the processing repeatability of the traveling wave tube. The technical characteristics show that the microstrip meander line slow-wave junction provided by the invention is a slow-wave structure suitable for a miniaturized traveling wave tube.
Description
Technical Field
The invention belongs to the field of vacuum electronics, and particularly relates to a microstrip meander line slow wave structure.
Background
Millimeter waves are electromagnetic spectrum between microwave and infrared, and correspond to a frequency range of 30GHz to 300GHz, and in practical applications, people often reduce the frequency of millimeter waves to 18 GHz. The millimeter wave has the characteristics of wide frequency band, relatively narrow wave beam, all-weather work, easy integration, miniaturization and the like, so that the millimeter wave has wide application prospect in the fields of millimeter wave radar and guidance systems, electronic countermeasure field, millimeter wave remote sensing, millimeter wave communication and the like. Millimeter wave technology enables modern communication systems to transmit larger amounts of information, greatly broadens communication frequency bands, provides non-interfering channels for more users, and simultaneously provides high-quality electromagnetic compatibility characteristics for various electronic systems. Therefore, the millimeter wave technology has great significance for developing national economy and consolidating national defense.
The development and application of millimeter wave technology have made urgent demands for miniaturized broadband and high-power millimeter wave sources. The traveling wave tube based on vacuum electronics is a millimeter wave radiation source with characteristics of high power and wide frequency band. When the traditional traveling wave tube works, a magnetic focusing system with excellent performance and a stable high-voltage power supply are needed, so that the size and the weight of the traveling wave tube are both large, the repeatability of the device is poor, and the cost of a single device is also extremely high. Therefore, the development of a traveling wave tube with a simple structure, low cost and miniaturization becomes a key for promoting the development of millimeter wave technology.
Disclosure of Invention
Aiming at the defects or improvement requirements of the prior art, the invention provides a micro-strip zigzag slow-wave structure, which mainly solves the problems of miniaturization of a traveling wave tube, simplification of the slow-wave structure, adaptation to a semiconductor processing technology, improvement of transmission characteristics, improvement of electric field distribution and the like.
In order to achieve the above object, the present invention provides a microstrip meander line slow wave structure, including: a microstrip meander line structure;
the microstrip zigzag line structure comprises a medium substrate and a metal patch layer positioned on the medium substrate, wherein the metal patch layer is formed by alternately arranging U-shaped metal wires and rectangular metal wires.
In some alternative embodiments, the U-shaped metal lines and the rectangular metal lines take different line widths.
In some alternative embodiments, the microstrip meander line slow wave structure further comprises an input-output waveguide matched to the microstrip meander line structure.
In some alternative embodiments, there is a transition waveguide structure between the input-output waveguide and the microstrip meander line structure.
In some alternative embodiments, the transition waveguide structure is a non-standard rectangular waveguide structure.
In some optional embodiments, a section of microstrip probe is added to each of the front end and the rear end of the microstrip line in the microstrip zigzag line structure, and the microstrip probe is inserted into each corresponding transition waveguide structure.
In some optional embodiments, the microstrip meander line slow wave structure further comprises a metal cavity carrying the microstrip meander line structure.
In general, compared with the prior art, the above technical solution contemplated by the present invention can achieve the following beneficial effects:
(1) the invention provides a microstrip zigzag line slow-wave structure which is suitable for a miniaturized traveling wave tube amplifier, designs a microstrip zigzag line structure formed by a microstrip line of a U-shaped patch modification and a dielectric substrate, is a core component of the slow-wave structure, and achieves the purposes of simplifying the slow-wave structure, improving the transmission characteristic of electromagnetic waves in the slow-wave structure and optimizing the distribution of an electric field. The invention has the advantages of simple and clear principle and strong engineering practicability, has the advantages of simple structure and easy processing and manufacturing through the modification optimization of the U-shaped microstrip line, and provides a feasible solution for reducing the processing difficulty of the traveling wave tube and improving the output characteristic of the traveling wave tube.
(2) The slow wave structure of the traditional traveling wave tube adopts an all-metal structure, and is realized by notching on metal, so that the processing difficulty is high, and the processing precision is difficult to guarantee. The invention adopts the planar microstrip zigzag line structure, is suitable for the technical processing of the printed circuit board with mature technology, does not need to carve grooves on metal, reduces the processing difficulty, has high processing precision and can reduce the volume of the traveling wave tube.
(3) The microstrip meander line slow wave structure designed by the invention has the characteristic of simple structure, can obtain better reflection characteristic by matching with an input-output structure, and has great advantage for improving the output characteristic of a traveling wave tube.
Drawings
Fig. 1 is a schematic view of a microstrip meander line slow wave line provided in an embodiment of the present invention, in which an upper U-shaped metal line is a microstrip line, and a lower rectangle is a dielectric substrate;
fig. 2 is a schematic diagram of a microstrip meander line structure model provided by an embodiment of the present invention, (a) is a schematic diagram of a microstrip line unit, and (b) is a cross-sectional diagram of a microstrip meander line slow-wave structure;
FIG. 3 is a longitudinal electric field distribution of a microstrip meander-line slow-wave structure provided by an embodiment of the present invention;
fig. 4 is a schematic diagram of a microstrip meander line slow wave structure and an input/output structure thereof according to an embodiment of the present invention;
fig. 5 is a transmission characteristic curve of a microstrip meander line slow wave structure provided by an embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The invention designs a micro-strip zigzag slow-wave structure which can be applied to a miniaturized traveling wave tube as a wave injection interaction system of the micro-strip zigzag slow-wave structure, mainly solves the problems of miniaturization of the traveling wave tube, simplification of the slow-wave structure, adaptation to a semiconductor processing technology, improvement of transmission characteristics, improvement of electric field distribution and the like, and can be used as a high-frequency interaction structure of the miniaturized traveling wave tube. The size of the traveling wave tube can be reduced, the processing cost is reduced, the manufacturing repeatability of the traveling wave tube is improved, the traveling wave tube can be processed by using a printed circuit board technology, and the slow wave structure obtains good electromagnetic wave transmission characteristics by optimizing structural parameters.
The invention provides a micro-strip zigzag line slow wave structure, which is technically characterized in that:
(1) a slow-wave structure with microstrip zigzag line is composed of microstrip zigzag line structure, input-output coupled structure, and transmission characteristics simulation.
(2) The structure design of the microstrip meander line: a metal patch and a dielectric substrate in a specific form are designed to form a microstrip zigzag line structure.
(3) The input and output coupling structure design: through the optimized design of the input and output structure, a structure matched with the microstrip meander line is formed, and the input and output structure with low reflection and low loss is formed.
(4) Simulation of transmission characteristics: and (3) constructing a simulation model in CST, and performing simulation calculation on the transmission characteristics of the model by using a time domain solver in CST.
The method comprises the following specific steps:
the microstrip zigzag slow wave structure is composed of a microstrip zigzag line, an input-output waveguide and a metal cavity, wherein the microstrip zigzag line is a core part of the slow wave structure.
1. Microstrip meander line structure design
Firstly, a metal patch layer is designed, the metal patch layer is formed by combining and synthesizing a U-shaped metal line part and a rectangular metal line part, the U-shaped metal line part and the rectangular metal line part adopt different line widths, and the patch layer with the microstrip zigzag lines is formed by periodic repetition, as shown in figure 1. The dielectric substrate is selected from Rogers RT5880, the dielectric constant is 2.2, the loss tangent angle is 0.0009, and the magnetic permeability is 1.0.
The microstrip zigzag line slow-wave structure provided by the invention is remarkably characterized in that the microstrip zigzag line is formed by combining a U-shaped metal line with unequal line width and a rectangular metal line through the modified design of the U-shaped metal line, so that the electric field distribution and the transmission characteristic of the slow-wave structure can be improved. FIG. 2 is a schematic diagram of a microstrip meander line structure model, in which (a) is a microstrip lineThe unit schematic diagram, and (b) is the cross section diagram of the microstrip meander line slow wave structure. The parameter p in FIG. 2 denotes the period length, b denotes the lateral width of the metal line, w1Representing the line width, w, of the rectangular portion of the metal line2Showing the line width of the U-shaped part of the metal wire, a showing the transverse width of the dielectric substrate, h showing the height of the rectangular cavity of the slow wave structure, and hsRepresenting dielectric substrate thickness and t representing metal line thickness. Through the simulation optimization design of parameters in fig. 2, the final design parameters are as follows: p is 0.14mm, a is 0.96mm, b is 0.50mm, w1＝0.02mm，w2＝0.03mm，h＝0.90mm，hs＝0.04mm，t＝0.005mm。
The eigen-mode solver is used to simulate the designed microstrip meander line slow-wave structure to obtain the longitudinal electric field distribution, as shown in fig. 3. The longitudinal electric field is concentrated around the metal wire, maintaining a relatively large intensity. Is favorable for the interaction between the electron beam and the electromagnetic wave.
2. Input-output coupling structure design
In order to feed or transmit electromagnetic wave signals in the external circuit and the slow wave structure without loss or with low loss, the input/output structure of the slow wave structure needs to be designed. By adding a section of transition waveguide structure (as the part marked by the dashed frame in fig. 4, a section of rectangular cavity structure) between the input/output standard waveguide and the slow wave structure, the slow wave structure can be well matched with the input/output standard waveguide. As shown in fig. 4, which is a schematic diagram of a microstrip meander line slow-wave structure and an input-output structure thereof, the whole cavity material (including an input-output transition structure and a wave injection interaction structure) is made of high-conductivity oxygen-free copper, and the conductivity is 5.8 × 107And (5) S/m. The transition section adopts a non-standard rectangular waveguide structure, the size of the wide side is 0.5mm, and the size of the narrow side is 0.35 mm. And a section of microstrip probe is respectively added at the front end and the rear end of the microstrip line, and the microstrip probe is inserted into the transition waveguide structure, so that the transmission of the electromagnetic wave between the microstrip meander line and an external circuit is realized. The designed waveguide-microstrip probe structure has the advantages of small standing wave, low reflection, low loss and the like, and the transmission characteristic of the slow wave structure can be improved to the greatest extent by optimizing the sizes of the transition waveguide and the microstrip probe.
3. Simulation of transmission characteristics
The transmission characteristics of the slow wave structure directly influence the interaction performance of the electron beam and the electromagnetic wave, and only when more electromagnetic waves are fed into the slow wave structure, the electron beam and the electromagnetic waves can effectively interact. In addition, the transmission characteristics will also directly affect the flatness of the operating bandwidth and gain of the traveling wave tube. Generally, before the injection wave interaction simulation is performed, transmission characteristic simulation is required, and whether the design of the slow wave structure is reasonable or not is judged through the transmission characteristic, so that whether a wider working bandwidth and a flatter gain curve can be obtained or not is judged. The transmission characteristics were mainly examined for the reflection coefficient S11 and the transmission coefficient S21.
In the CST software, a time domain solver is used to perform simulation calculation on the microstrip meander line slow-wave structure, and a transmission characteristic curve of the slow-wave structure is obtained after numerical processing, as shown in fig. 5. As can be seen from FIG. 5, in the wide frequency band range of 25GHz to 40GHz, the reflection coefficient S11 of the designed microstrip meander line slow-wave structure is less than-20 dB, and the transmission coefficient S21 is greater than-1.5 dB. The slow wave structure has good transmission characteristics and can be used as a high-frequency structure of a traveling wave tube.
According to the microstrip meander line slow wave structure provided by the invention, better transmission characteristics are obtained through the modified design of the microstrip metal line and the optimized design of the transition waveguide and the microstrip probe. Meanwhile, the microstrip zigzag slow wave structure provided by the invention has the advantages of simple structure, small size and the like, is suitable for technical processing of printed circuit boards, and can reduce the volume of a traveling wave tube, reduce the processing cost of the traveling wave tube and improve the processing repeatability of the traveling wave tube. The technical characteristics show that the microstrip meander line slow-wave junction provided by the invention is a slow-wave structure suitable for a miniaturized traveling wave tube.
It should be noted that, according to the implementation requirement, each step/component described in the present application can be divided into more steps/components, and two or more steps/components or partial operations of the steps/components can be combined into new steps/components to achieve the purpose of the present invention.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (7)
1. A microstrip meander line slow wave structure, comprising: a microstrip meander line structure;
the microstrip zigzag line structure comprises a medium substrate and a metal patch layer positioned on the medium substrate, wherein the metal patch layer is formed by alternately arranging U-shaped metal wires and rectangular metal wires.
2. The microstrip meander line slow wave structure of claim 1, wherein the U-shaped metal line and the rectangular metal line have different line widths.
3. The microstrip meander line slow wave structure of claim 1 or 2, further comprising: and the input and output waveguides are matched with the microstrip meander line structure.
4. The microstrip meander line slow wave structure of claim 3, wherein a transition waveguide structure exists between the input and output waveguides and the microstrip meander line structure.
5. The microstrip meander line slow wave structure of claim 4, wherein the transition waveguide structure is a non-standard rectangular waveguide structure.
6. The microstrip meander line slow wave structure of claim 5, wherein a microstrip probe is added to each of the front and rear ends of the microstrip line in the microstrip meander line structure, and the microstrip probe is inserted into the corresponding transition waveguide structure.
7. The microstrip meander line slow wave structure of claim 6, further comprising a metal cavity carrying the microstrip meander line structure.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114530359A (en) * | 2022-02-22 | 2022-05-24 | 电子科技大学 | Coaxial multichannel suspended microstrip line slow-wave structure traveling wave tube |
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2020
- 2020-11-25 CN CN202011339480.6A patent/CN112466731A/en active Pending
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Cited By (2)
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