A TE 11 Working mode ultra-wideband metasurface output window structure

Abstract

The present invention discloses a TE 11 The invention discloses an ultra-wideband metasurface output window structure in working mode, which belongs to the technical field of vacuum electron cyclotron devices. It includes a middle dielectric sheet, and cylindrical arrays are respectively arranged on both sides of the middle dielectric sheet as matching layers. The invention arranges the matching layer as a cylindrical array so that the equivalent dielectric constant #imgabs0# of the matching layer satisfies the dielectric constant ε of the intermediate dielectric layer. r The square root value of , thereby reducing reflection and increasing the bandwidth of the output window in the gyrotron traveling wave tube.

Description

Technical Field

[0001] The present invention belongs to the technical field of vacuum electron cyclotron devices, and in particular relates to a TE for use in a cyclotron traveling wave tube. 11 Working mode ultra-wideband metasurface output window structure. Background Art

[0002] From the electromagnetic wave predicted by Maxwell to the emergence of vacuum electronic devices, an important source of electromagnetic wave radiation, it is an important achievement in this field. At present, microwave devices have been well applied in the microwave band, but have encountered many difficulties in the millimeter wave band and even higher frequency bands. Due to the mechanism of the coexistence of the size and working wavelength of traditional vacuum electronic devices, that is, as the working frequency expands to higher frequency bands, the processing technology will greatly increase the difficulty of processing due to the smaller size structure, so that the development of traditional vacuum electronic devices towards higher frequency millimeter wave bands and even submillimeter wave bands will encounter a series of problems. The emergence of gyrotron traveling wave tube devices solves this problem. In theory, the size of gyrotron traveling wave tube devices is not affected by the operating frequency. When the operating frequency increases, as long as the magnetic field is large enough, the gyrotron device can work effectively, and the gyrotron traveling wave tube device can obtain very high power, thereby driving the radar.

[0003] The gyrotron traveling wave tube uses the interaction between the electron beam and the working mode to transfer the energy of the high-speed electrons to the working mode, thereby amplifying the input microwave signal. Therefore, the gyrotron traveling wave tube is a fast-wave, high-power, wide-bandwidth amplifier, but studies have shown that the bandwidth of the gyrotron traveling wave tube is often limited by the working bandwidth of the output window, and the gyrotron traveling wave tube needs a high vacuum internal environment to operate reliably. Therefore, the output window is one of the key components of the gyrotron traveling wave tube, and its performance will directly affect the overall performance of the gyrotron traveling wave tube. The thickness of the window in the output window is one of the key parameters in the design. If its design is unreasonable, it will cause the energy of the signal output by the high-frequency structure part to enter the output window and reflect into the high-frequency structure to increase, making the high-frequency structure of the gyrotron traveling wave tube extremely unstable, disrupting the beam-wave interaction of the high-frequency structure part, and thus affecting its performance. In addition, due to the existence of dielectric loss in the output window material, when the electromagnetic wave passes through the window with large dielectric loss, a high heat will be generated in the window, which will cause the window temperature to be too high and cause the window to break. Therefore, a low-reflection, wide-bandwidth, and high-power output window is of great significance for improving the overall performance of the gyrotron traveling wave tube. Summary of the invention

[0004] In view of the problem that the dielectric constants of the intermediate dielectric layer and the matching layer in the multi-layer output window structure do not match, resulting in a narrow operating frequency band of the output window, the present invention proposes a TE 11The working mode is an ultra-wideband metasurface output window structure. By setting the matching layer as a cylindrical array, the equivalent dielectric constant of the matching layer is Satisfy the dielectric constant ε of the intermediate dielectric layer r The square root value of , thereby increasing the bandwidth of the output window in the gyrotron traveling wave tube.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A TE 11 The working mode ultra-wideband metasurface output window structure is characterized by comprising a middle-layer dielectric sheet, and cylindrical arrays are respectively arranged on both sides of the middle-layer dielectric sheet as matching layers; the cylindrical array comprises a plurality of uniformly arranged cylindrical structures.

[0007] Furthermore, the thickness t of the middle-layer dielectric sheet is 0.52; the period w of the cylindrical structure is 0.56 mm; the height h of the cylindrical structure is 0.44 mm, the inner radius r2 of the cylindrical structure is 0.1 mm, and the outer radius r1 is 0.22 mm.

[0008] Furthermore, the cylindrical structure is made of the same material as the single-layer dielectric window.

[0009] Furthermore, the material of the cylindrical structure and the material of the single-layer dielectric window are beryllium oxide.

[0010] The cylindrical array output window structure based on the matching layer principle has the following advantages:

[0011] (1) It has an ultra-wide bandwidth and a high transmission coefficient. In the frequency band range of 77.5 GHz to 144 GHz, when the center frequency is 110.75 GHz, its relative bandwidth is 60.2%, and the transmission coefficient S is within the W and F bands. 21 Above -0.062dB.

[0012] (2) Beryllium oxide has relatively low dielectric loss and good heat dissipation performance, which makes it have relatively high power (pulse or average) capacity.

[0013] (3) The insertion loss is small, so it can avoid excessive dielectric loss causing excessive temperature and damage to the window.

[0014] (4) It has high mechanical strength and good heat dissipation performance, so it can adapt to changes in various environmental conditions and maintain its stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the three-dimensional structure of the output window of the present invention;

[0016] Figure 2It is a schematic diagram of the dimensions of the output window of the present invention;

[0017] Figure 3 It is a top view of the cylindrical structure;

[0018] Figure 4 is the S of the output window in the embodiment of the present invention 11 Parameter diagram;

[0019] Figure 5 is the S of the output window in the embodiment of the present invention 21 Parameter diagram.

[0020] In the figure: 1 is a cylindrical structure, and 2 is a middle-layer dielectric sheet. DETAILED DESCRIPTION

[0021] The technical solution of the present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0022] Figure 1 The output window structure of the metasurface of this embodiment is shown, including a middle-layer dielectric sheet, and cylindrical arrays are respectively arranged on both sides of the middle-layer dielectric sheet as matching layers; the cylindrical array includes a number of evenly arranged cylindrical structures. The radius R of the middle-layer dielectric sheet is 10 mm, the thickness t is 0.533 mm, and the material is beryllium oxide.

[0023] Usually the thickness of a single-layer window is an integer multiple of one-quarter of the waveguide wavelength, and according to the multi-layer matching principle, the equivalent dielectric constant of the matching layer material is satisfy The matching effect is best when ε r In this embodiment, beryllium oxide is also selected as the matching layer material, and the relative dielectric constant of the matching layer is adjusted by optimizing the structural dimensions of the matching layer, thereby achieving the best matching effect, expanding the bandwidth, and reducing reflection.

[0024] According to the design requirements of the output window, the radius R of the middle dielectric sheet is determined to be 10 mm. According to the theoretical formula λ c =2πR / μ′ mn , where μ′ mn is the m-th order Bessel function of the first kind J′ m (k c r) has a derivative equal to the nth root of zero, k c =μ′ mn / R is the cutoff beam. The working mode in this embodiment is TE 11 mode, so the corresponding μ′ mn =μ′ 11=3.83. In the frequency band from 77.5 GHz to 144 GHz, the center frequency f0 is 110.75 GHz, so the corresponding wavelength λ0 = c / f0, c is the speed of light, and λ c Substitute λ0 into formula (1) and formula (2):

[0025]

[0026]

[0027] Then through t = N × λ t / 2, and Where N is an integer value, N=1 is taken to determine the theoretical value of t as 0.533mm, and N=0 is taken to determine the theoretical value of h as 0.425mm. According to the value of λ0, the ranges of the inner radius r2, the outer radius r1 and the interval d between the outer walls of the given cylinder are 0.01×λ0~0.05×λ0, 0.05×λ0~0.12×λ0 and 0.02×λ0~0.1×λ0, respectively, and the value of (2r1+d) should be less than λ0 / 4. The initial values ​​of the three parameters of inner radius r2, outer radius r1 and interval d are selected, modeling and simulation optimization are carried out to obtain the optimized model. The output window size parameter values ​​in this embodiment are shown in Table 1.

[0028] Table 1

[0029] parameter <![CDATA[r1]]> <![CDATA[r2]]> d h t Value(mm) 0.22 0.1 0.12 0.44 0.52

[0030] Figure 4 is the reflection coefficient S of the output window of this embodiment 11 The simulation result diagram shows that within the frequency band range of 77.5GHz to 144GHz, when the center frequency is 110.75GHz, the reflection coefficient is less than -19dB and the relative bandwidth is 60.2%, which significantly improves the bandwidth of the output window.

[0031] Figure 5 is the transmission coefficient S of the output window of this embodiment 21 Simulation results show that the transmission coefficient S 21 Greater than -0.062dB, with good transmission performance.

Claims

1. A TE 11 The working mode ultra-wideband metasurface output window structure is characterized by: It comprises a middle-layer dielectric sheet, and cylindrical arrays are respectively arranged on two sides of the middle-layer dielectric sheet as matching layers; the cylindrical arrays comprise a plurality of evenly arranged cylindrical structures; The thickness t of the middle-layer dielectric sheet is 0.52 mm; the period w of the cylindrical structure is 0.56 mm; the height h of the cylindrical structure is 0.44 mm; the inner radius r2 of the cylindrical structure is 0.1 mm, and the outer radius r1 is 0.22 mm.

2. A TE as claimed in claim 1 11 The working mode ultra-wideband metasurface output window structure is characterized by: The cylindrical structure is made of the same material as the single-layer dielectric window.

3. A TE as claimed in claim 1 11 The working mode ultra-wideband metasurface output window structure is characterized by: The material of the cylindrical structure and the material of the single-layer dielectric window are beryllium oxide.

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