A slit-type staggered double-gate waveguide slow wave structure

Abstract

This invention discloses a slit-type staggered dual-grid waveguide slow-wave structure. Each single-period structure includes a metal shell, an upper metal grid, and a lower metal grid. The upper and lower metal grids are staggered in a half-period pattern, and a rectangular electron beam channel exists between them. A notch is provided at the lower edge of the upper metal grid and the upper edge of the lower metal grid, respectively. Each notch has the same shape and size, and the notches in either the upper or lower metal grid are symmetrically distributed. The invention reduces the loss and dispersion characteristics of the staggered dual-grid waveguide slow-wave structure by creating notches on the staggered metal grids, forming vacuum slits connected to the electron beam channel, thereby further improving the output power and bandwidth of the traveling wave tube.

Description

Technical Field

[0001] This invention belongs to the field of waveguide slow wave structure technology, and more specifically, relates to a slit-type staggered double-grid waveguide slow wave structure. Background Technology

[0002] Terahertz (THz) waves refer to electromagnetic waves with frequencies ranging from 0.1 to 10 THz. Their unique properties have profound implications for fields such as communications (broadband communications), radar, electronic warfare, electromagnetic weapons, astronomy, medical imaging, non-destructive testing, and security inspection. However, the further development of terahertz technology is currently limited by the availability of practically applicable terahertz radiation sources; therefore, the exploration of terahertz radiation sources is urgently needed.

[0003] Based on the frequency range of terahertz waves, the generation of terahertz radiation sources can be explored from both photonics and electronics perspectives. From an electronics perspective, terahertz radiation sources can be divided into solid-state electronic and vacuum electronic terahertz radiation sources. Vacuum electronic terahertz radiation sources mainly include traveling wave tubes (TWTs), backward wave tubes (WRTBs), extended interaction devices (IDEDs), gyrotrons, and Oro tubes, among other vacuum electronic devices. Among these, traveling wave tubes offer advantages such as wide bandwidth, high gain, high efficiency, high stability, and long lifetime.

[0004] The main module that determines the performance of a traveling wave tube is the slow wave structure. Among the many different types of slow wave structures, the interlaced double-grid waveguide slow wave structure is a common strip injection slow wave structure. It not only has high gain characteristics and a relatively wide operating bandwidth, but its all-metal structure can also significantly improve the power capacity and stability of the traveling wave tube, thereby obtaining higher output power. Figure 1 This is a schematic diagram of a traditional interleaved double-grating waveguide slow wave structure. Figure 1 (a) is a schematic diagram of a single-cycle three-dimensional structure. To better show the internal structure, half of the upper part of the structure is hidden. p represents the cycle length and s represents the thickness of the upper / lower metal grid. Figure 1 (b) is a front view of the single-cycle structure, where hg represents the height of the upper / lower metal gate, ht represents the height of the electron beam channel, and wg represents the width of the upper / lower metal gate. Figure 2 This is a schematic diagram of the dispersion curves of a traditional staggered double-grating waveguide slow-wave structure with different metal grating heights. Figure 2 The structure used is a traditional interlaced dual-grid waveguide slow-wave structure with zero slits (0-slit). For example... Figure 2As shown, the upper cutoff frequency of a traditional interleaved double-grid waveguide slow-wave structure decreases with increasing metal grid height hg, while the lower cutoff frequency remains constant. Studies have revealed that as the operating frequency increases, especially into the terahertz band, the output power of the traveling wave tube (TWT) with the interleaved double-grid waveguide slow-wave structure drops sharply due to increased surface metal losses. In this situation, to achieve high output power, the bandwidth characteristics of the TWT often cannot be simultaneously maintained. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a double-slit staggered double-grid waveguide slow wave structure. By setting notches on the upper and lower staggered metal grids, a vacuum slit connected to the electron beam channel is formed, which reduces the loss and dispersion characteristics of the staggered double-grid waveguide slow wave structure, thereby further improving the output power and bandwidth of the traveling wave tube.

[0006] To achieve the above-mentioned objectives, the present invention provides a slit-type staggered dual-grating waveguide slow-wave structure. Each single-period structure includes a metal shell, an upper metal grating, and a lower metal grating. The upper and lower metal gratings are staggered in a semi-period manner, and a rectangular electron beam channel exists between the upper and lower metal gratings. The invention is characterized by:

[0007] Set at the lower edge of the upper metal grid and the upper edge of the lower metal grid respectively. A gap, Each notch has the same shape and size; in a single-cycle structure, a coordinate system is constructed with the center of the electron beam channel as the origin, the horizontal direction as the X-axis, the vertical direction as the Y-axis, and the electron beam direction as the Z-axis. The upper or lower metal grid... The projections of the notches onto the XY plane are symmetrically distributed about the Y-axis, and the upper metal grille... A gap and the lower metal grille The projections of the gaps onto the XY plane are symmetrical about the X-axis.

[0008] This invention relates to a slit-type staggered dual-grating waveguide slow-wave structure. Each single-period structure includes a metal shell, an upper metal grating, and a lower metal grating. The upper and lower metal gratings are staggered in a half-period pattern, and a rectangular electron beam channel exists between the upper and lower metal gratings. A rectangular electron beam channel is provided at the lower edge of the upper metal grating and the upper edge of the lower metal grating. A gap, Each notch has the same shape and size, with either an upper or lower metal grille. The gaps are symmetrically distributed, and the upper metal grid... A gap and the lower metal grille The gaps are also symmetrically distributed.

[0009] The present invention has the following beneficial effects:

[0010] 1) By setting notches in the upper and lower metal grids to form a vacuum slit connected to the electron beam channel, the present invention can reduce the lower cutoff frequency of the staggered double-grid waveguide slow wave structure. It can be further combined with the method of reducing the grid height to increase the upper cutoff frequency, so that the bandwidth of the entire slow wave structure can be significantly improved.

[0011] 2) This invention can reduce the loss of the staggered dual-grid waveguide slow wave structure, thereby improving the output power. This has a particularly significant advantage in the terahertz band where loss attenuation is the dominant factor.

[0012] 3) The present invention has a simple structure and is easy to manufacture. By changing the slit size, the output characteristics of the traveling wave tube can be significantly changed, which has certain engineering application significance.

[0013] 4) Under the same operating conditions, whether the metal grid width wg or the metal grid height hg is kept constant, the high-frequency characteristics and PIC simulation results show that the slit-type staggered double-grid waveguide slow wave structure has lower loss and wider bandwidth characteristics, which fully proves the feasibility of enhancing the bandwidth of traveling wave tube based on this slow wave structure. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of a traditional interleaved dual-grating waveguide slow-wave structure;

[0015] Figure 2 This is a schematic diagram of the dispersion curves of a traditional staggered double-grating waveguide slow-wave structure under different metal grating heights;

[0016] Figure 3 This is a structural diagram illustrating a specific embodiment of the slit-type interlaced dual-grid waveguide slow-wave structure of the present invention;

[0017] Figure 4 This is a schematic diagram of the dispersion curves of slow-wave structures with zero slits and double slits interlaced double-grid waveguides under different metal grid widths;

[0018] Figure 5 This is a vacuum model diagram of a traveling wave tube based on a slow wave structure with double slits and interlaced double grids in this embodiment;

[0019] Figure 6 This is a schematic diagram of the parameters of the five slow-wave structures in this embodiment;

[0020] Figure 7 This is a comparison diagram of the dispersion curves of the five slow-wave structures in this embodiment;

[0021] Figure 8 This is a comparison diagram of the normalized phase velocity curves of the five slow-wave structures in this embodiment;

[0022] Figure 9This is a comparison diagram of the interaction impedance curves of the five slow-wave structures at the center point of the electron beam channel in this embodiment;

[0023] Figure 10 This is a comparison of the dispersion characteristics of the 2-slit staggered dual-grating waveguide slow wave structure in this embodiment under different slit distances;

[0024] Figure 11 This is a comparison of the dispersion characteristics of the 2-slit staggered dual-grating waveguide slow wave structure in this embodiment at different slit heights;

[0025] Figure 12 This is a comparison of the dispersion characteristics of the 2-slit staggered dual-grating waveguide slow wave structure in this embodiment under different slit widths;

[0026] Figure 13 This is a comparison of the dispersion curves of the three types of traveling wave tubes in this embodiment;

[0027] Figure 14 This is a comparison of the normalized phase velocity curves of the three types of traveling wave tubes in this embodiment;

[0028] Figure 15 This is a comparison of the interaction impedance curves of three types of traveling wave tubes.

[0029] Figure 16 This is a comparison of the normalized group velocity curves of the three types of traveling wave tubes in this embodiment;

[0030] Figure 17 This is a comparison diagram of the reflection coefficient S11 of the three traveling wave tubes in this embodiment under 20 cycles.

[0031] Figure 18 This is a comparison diagram of the transmission coefficient S21 of the three traveling wave tubes in this embodiment under the condition of 20 cycles;

[0032] Figure 19 This is a comparison of the output power versus frequency curves of the three types of traveling wave tubes in this embodiment;

[0033] Figure 20 This is a comparison of the output gain versus frequency curves of the three types of traveling wave tubes in this embodiment. Detailed Implementation

[0034] The specific embodiments of the present invention will now be described with reference to the accompanying drawings to enable those skilled in the art to better understand the invention. It should be particularly noted that in the following description, detailed descriptions of known functions and designs that might obscure the main content of the invention will be omitted here.

[0035] Example

[0036] Figure 3This is a structural diagram illustrating a specific embodiment of the slit-type interlaced dual-grid waveguide slow-wave structure of the present invention. Figure 3 (a) is a schematic diagram of a single-cycle three-dimensional structure. To better show the internal structure, half of its upper part is hidden. (b) is a front view of the single-cycle structure. Figure 3 As shown, the slit-type interlaced double-grating waveguide slow-wave structure of this invention is similar to the traditional interlaced double-grating waveguide slow-wave structure, including a metal shell 1, an upper metal grating 2, and a lower metal grating 3. The upper metal grating 2 and the lower metal grating 3 are interlaced in a semi-periodic manner, and a rectangular electron beam channel 4 exists between the upper metal grating 2 and the lower metal grating 3. The difference lies in that this invention has a rectangular electron beam channel 4 located at the lower edge of the upper metal grating 2 and the upper edge of the lower metal grating 3. There are 5 gaps. Each notch 5 has the same shape and size. In the single-cycle structure, a coordinate system is constructed with the center of the electron beam channel as the origin, the horizontal direction as the X-axis, the vertical direction as the Y-axis, and the electron beam direction as the Z-axis. The upper metal grid 2 or the lower metal grid 3... The projections of the notches onto the XY plane are symmetrically distributed about the Y-axis, and the upper metal grid 2... A gap and lower metal grille 3 The projections of the gaps onto the XY plane are symmetrical about the X-axis.

[0037] As described above, by setting notches 5 in the upper metal grid 2 and the lower metal grid 3, gaps can be formed above and below the rectangular electron beam channel 4, respectively. A vacuum slit connected to a rectangular electron injection channel 4. Figure 3 The number of gaps in the middle 5 Therefore, two vacuum slits are formed above and below the rectangular electron beam channel 4, respectively.

[0038] Taking into account both the ease of processing and the technical effect, in this embodiment, the notch 5 is set as a cuboid, and its width is... The preferred value range is ,in This represents the width of the upper metal gate 2 / lower metal gate 3; the preferred value range for the height is... ,in This indicates the width of the notch in the cuboid. Additionally, it indicates the number of notches (5). Preferably set to even numbers, with 2 and 4 being better values, where the distance between gaps 5 is... The preferred value range is .

[0039] Figure 4 This is a schematic diagram of the dispersion curves for slow-wave structures of zero-slit and double-slit staggered double-grid waveguides with different metal grid widths. Figure 4It is known that the cutoff frequency of the traditional 0-slit interlaced double-grid waveguide slow-wave structure decreases as wg increases. With a fixed metal grid width wg, the cutoff frequency of the 2-slit interlaced double-grid waveguide slow-wave structure is lower than that of the 0-slit interlaced double-grid waveguide slow-wave structure. This means that the effect of inserting two slits into the existing metal grid is not significantly different from the effect of increasing the metal grid width wg. However, after inserting two slits, the decrease in the lower cutoff frequency of the slow-wave structure is greater than that of the upper cutoff frequency. Therefore, compared to increasing the grid width wg, the 2-slit interlaced double-grid waveguide slow-wave structure has a wider bandwidth and smoother dispersion, which will further enhance the bandwidth.

[0040] Figure 5 This is a vacuum model diagram of a traveling wave tube based on a slow-wave structure with double slits and interlaced double-grid waveguides in this embodiment. Figure 5 As shown, the traveling wave tube vacuum model includes a high-frequency signal input port 51, an input rectangular coupling aperture 52, an electron beam emitter port 53, a slow-wave structure 54, an electron collector port 55, an output rectangular coupling aperture 56, a high-frequency signal output port 57, a double-slit channel 58, and an elliptical electron beam channel 59. The specific dimensions of the high-frequency signal input port 51 are consistent with those of the standard rectangular waveguide WR-1.5. The use of the elliptical electron beam channel 59 ensures that signals within the operating frequency band are always cut off when passing through the electron beam emitter port 53 and the electron collector port 55, thus avoiding any impact on the input and output signals. Figure 5 The number of periods in the medium-slow wave structure is 10.

[0041] To better illustrate the technical effects of this invention, specific examples are used to verify its simulation. In this embodiment, the high-frequency characteristics of different slow-wave structures are compared and verified. In this embodiment, the phase of the slow-wave structure is fixed at 450°, i.e., phase=450°, and the intrinsic frequency corresponding to this phase is 670GHz. Under this condition, the designed traveling-wave tube will have the same synchronization voltage. Based on this, five slow-wave structures are designed based on zero-slit (0-slit) and slit (N-slit) staggered dual-grid waveguide slow-wave structures. Figure 6 This is a schematic diagram of the parameters of the five slow-wave structures in this embodiment. For example... Figure 6As shown, keeping other parameters constant, to achieve an intrinsic frequency of 670 GHz at phase = 450°, slow-wave structure 1 uses a traditional 0-slit interleaved dual-gate waveguide slow-wave structure with a metal gate height of hg = 210 μm; slow-wave structures 2 to 5 use N-slit interleaved dual-gate waveguide slow-wave structures with slit numbers N = 1, 2, 3, 4, and a metal gate height of hg = 110 μm; the slit heights hs are 100 μm, 52 μm, 27 μm, and 16 μm, respectively. This means that compared to the 0-slit interleaved dual-gate waveguide slow-wave structure, at the same center frequency, the N-slit (N = 1-4) interleaved dual-gate waveguide slow-wave structure has a lower metal gate height hg value, which will help reduce the aspect ratio of the fabrication dimensions, thus making the device structure easier to fabricate. Furthermore, Figure 6 The slits inserted in the N-slit (N = 1-4) staggered double-grating waveguide slow-wave structure shown have the same slit width ws and slit spacing ds, with ws = ds = 30 μm. As shown in the figure, to satisfy the condition of an intrinsic frequency of 670 GHz at phase = 450°, the slit height hs gradually decreases as the number of inserted slits N increases.

[0042] Figure 7 This is a comparison of the dispersion curves of the five slow-wave structures in this embodiment. Figure 7 It can be seen that, under the conditions of phase=450° and intrinsic frequency of 670GHz, the bandwidth of the N-slit (N=1-4) staggered double-grid waveguide slow wave structure is greater than that of 0-slit, and the more slits inserted, the wider the bandwidth.

[0043] Figure 8 This is a comparison of the normalized phase velocity curves for the five slow-wave structures in this embodiment. Figure 7 It can be seen that, under the conditions of phase=450° and intrinsic frequency of 670GHz, the dispersion of the N-slit (N = 1-4) staggered double-grating waveguide slow wave structure is more gentle than that of 0-slit. Moreover, the more slits are inserted, the gentler the normalized phase velocity curve becomes, which has a significant advantage for obtaining a wider bandwidth.

[0044] Figure 9 This is a comparison of the interaction impedance curves of the five slow-wave structures at the center point of the electron beam channel in this embodiment. Figure 9It can be seen that, under the conditions of phase=450° and intrinsic frequency of 670GHz, due to the smoother dispersion curve, the interaction impedance of the N-slit (N = 1-4) staggered double-grid waveguide slow-wave structure at the center point of the electron beam channel is generally less than that of the 0-slit structure. Furthermore, the more slits inserted, the smaller the interaction impedance. Notably, the interaction impedance is greater when N is even than when N is odd, and the interaction impedance of the 1-slit staggered double-grid waveguide slow-wave structure at the center point of the electron beam channel is close to 0. Calculation of the average interaction impedance in the electron beam interaction region reveals a distribution pattern consistent with the above, but with a slightly increased interaction impedance value.

[0045] Studies have found that appropriately changing the size parameters of the inserted slits can make the dispersion curve smoother. Since the more slits inserted, the higher the processing requirements and the more complex the structure, this embodiment only considers the case of inserting two slits (2-slit) for slit size parameter simulation. To fully illustrate the influence of the various slit size parameters of the present invention on the staggered dual-grid waveguide slow-wave structure, the phase is also fixed at phase=450°, and the corresponding intrinsic frequency is 670GHz. While keeping other size parameters constant, the dispersion characteristics are simulated for different slit distances ds, slit heights hs, and slit widths ws.

[0046] Figure 10 This is a comparison of the dispersion characteristics of a 2-slit staggered double-grating waveguide slow-wave structure at different slit distances. Figure 10 The slit height hs = slit width ws = 30 μm, Kc represents the interaction impedance, and Vp / c represents the normalized phase velocity. Figure 10 It can be seen that as the slit distance ds gradually increases, the entire interaction impedance curve and normalized phase velocity curve of the slow wave structure gradually shift to the left, and the dispersion curve becomes flatter.

[0047] Figure 11 This is a comparison of the dispersion characteristics of a 2-slit staggered double-grating waveguide slow-wave structure at different slit heights. Figure 11 The distance between the slits, ds, equals the slit width, ws, which is 30 μm. (From...) Figure 11 It can be seen that as the slit height hs gradually increases, the entire interaction impedance curve and the normalized phase velocity curve of the slow wave structure gradually shift to the left, and the interaction impedance gradually increases.

[0048] Figure 12 This is a comparison of the dispersion characteristics of a 2-slit staggered double-grating waveguide slow-wave structure under different slit widths. Figure 12 The distance between the slits, ds, equals the slit height, hs, which is 30 μm. (From...) Figure 12It can be seen that as the slit width ws gradually increases, the entire interaction impedance curve and normalized phase velocity curve of the slow wave structure gradually shift to the left, the dispersion curve becomes flatter, and the decrease in the lower cutoff frequency is greater than the decrease in the upper cutoff frequency.

[0049] Based on the above analysis, it can be concluded that increasing the slit distance ds or the slit width ws can make the dispersion curve smoother, thereby obtaining a wider bandwidth.

[0050] To fully illustrate the bandwidth enhancement method described in this invention, based on the above analysis, a slow-wave structure using a zero-slit (0-slit) and double-slit (2-slit) interleaved dual-grating waveguide is employed. Figure 5 The input / output structure design scheme shown includes three types of traveling wave tubes: Type 1: 0-slit: wg=235μm, hg=210μm; Type 2: 0-slit: wg=247μm, hg=120μm; Type 3: 2-slit: wg=235μm, hg=120μm. It can be noted that the first and third types of traveling wave tubes have the same grid width wg, while the second and third types have the same grid height hg. Table 1 shows the specific structural dimensions and parameters of the third type of double-slit (2-slit) staggered double-grid waveguide slow-wave structure in this embodiment.

[0051] ds Distance between slits 100 hg Metal grid height 120 hs Slit height 16 ht Electron injection channel height 60 p Period length 150 s Metal gate thickness 40 wg Metal gate width 235 ws Slit width 35

[0052] Table 1

[0053] Figure 13 This is a comparison of the dispersion curves of the three types of traveling wave tubes in this embodiment. Figure 13 It can be seen that when the phase of the three types of traveling wave tubes is 450°, the corresponding intrinsic frequency is 670 GHz. It can also be clearly seen that the passband between the upper and lower cutoff frequencies of the third type of traveling wave tube (2-slit: wg=235μm, hg=120μm) is significantly larger than that of the first type of traveling wave tube (0-slit: wg=235μm, hg=210μm) with the same gate width wg and the second type of traveling wave tube (0-slit: wg=247μm, hg=120μm) with the same gate height hg.

[0054] Figure 14 This is a comparison of the normalized phase velocity curves of the three types of traveling wave tubes in this embodiment. Figure 14 It can be seen that the three types of traveling wave tubes have the same synchronization voltage at 670 GHz, and it can be clearly seen that the dispersion of the third type of traveling wave tube (2-slit: wg=235μm, hg=120μm) is significantly weaker than that of the first and second types of traveling wave tubes, that is, the third type of traveling wave tube will have a wider bandwidth.

[0055] Figure 15 This is a comparison of the interaction impedance curves of three types of traveling wave tubes. Figure 15 It can be seen that, due to its weaker dispersion characteristics, the third type of traveling wave tube (2-slit: wg=235μm, hg=120μm) has the weakest interaction impedance, while the first type of traveling wave tube (0-slit: wg=235μm, hg=210μm) with the same gate width wg has the strongest dispersion characteristics and the largest interaction impedance, which means it has a stronger interaction transduction capability.

[0056] Figure 16 This is a comparison of the normalized group velocity curves of the three types of traveling wave tubes in this embodiment. Figure 16 It can be seen that, due to the insertion of the double slits, the third type of traveling wave tube (2-slit: wg=235μm, hg=120μm) has the largest normalized group velocity compared to the first and second types without slit insertion. While the first type of traveling wave tube has the largest interaction impedance, its normalized group velocity is the smallest. The attenuation constant in the traveling wave tube... The expression is:

[0057]

[0058] in, Angular frequency, For group velocity, This is the quality factor.

[0059] From the above equation, we can see that the attenuation constant is... It is inversely proportional to the normalized group velocity. Further research revealed that the first type of traveling wave tube has a quality factor of 279 at phase = 450°, while the third type has a quality factor of 277. Figure 16 As can be seen from the above formula, the third type of traveling wave tube has weaker attenuation loss, while the first type of traveling wave tube has stronger attenuation loss.

[0060] Figure 17 This is a comparison chart of the reflection coefficient S11 of the three traveling wave tubes in this embodiment under 20 cycles. Figure 17 It can be seen that the first type of traveling wave tube (0-slit: wg=235μm, hg=210μm) has a bandwidth of 20GHz (660~680GHz); the second type of traveling wave tube (0-slit: wg=247μm, hg=120μm) has a bandwidth of 66GHz (645~711GHz); when the frequency is greater than 648 GHz, the reflection coefficient S11 of the third type of traveling wave tube (2-slit: wg=235μm, hg=120μm) is less than -15dB, and it has the widest bandwidth.

[0061] Figure 18 This is a comparison chart of the transmission coefficient S21 of the three traveling wave tubes in this embodiment under the condition of 20 cycles. Figure 18 It can be seen that although the first type of traveling wave tube (0-slit: wg=235μm, hg=210μm) has the largest interaction impedance, its transmission loss attenuation is also the largest, while the transmission loss attenuation of the third type of traveling wave tube is slightly greater than that of the second type.

[0062] To compare and verify the interaction performance of the three traveling wave tubes, it is necessary to ensure that all three tubes operate under the same conditions. Therefore, the operating current of all three tubes was set to 0.018 A, the electron beam width to be 120 μm, the electron beam height to be 40 μm, and the focusing magnetic field to be 1.2 T. The conductivity of the lossy oxygen-free copper was set to 2 × 10⁻⁶. 7 S / m is used to compare the output characteristics of the three traveling wave tubes. Table 2 is a comparison table of parameters and output characteristics of the three traveling wave tubes in this embodiment.

[0063] wg(μm) 235 247 235 hg(μm) 210 120 120 Saturation period number 190 210 210 Operating voltage (kV) 19.6 19.5 19.3 Frequency (GHz) 671 672 669 Output power (W) 1.91 2.66 2.74 Gain (dB) 32.81 34.24 34.38 Electronic efficiency 0.54% 0.76% 0.79% 3-dB bandwidth (GHz) 3 17 22

[0064] Table 2

[0065] As shown in Table 2, the first type of traveling wave tube (0-slit: wg=235μm, hg=210μm) has the largest interaction impedance and the smallest number of saturation periods, 190 periods. The second and third types of traveling wave tubes have similar interaction impedances and the same number of saturation periods, 210 periods. Furthermore, the third type of traveling wave tube (2-slit: wg=235μm, hg=120μm) has the lowest loss attenuation and the largest output power and saturation gain, at 2.74W and 34.38 dB respectively, with a corresponding electronic efficiency of 0.79%.

[0066] Figure 19 This is a comparison graph showing the relationship between the output power and frequency of the three types of traveling wave tubes in this embodiment. Figure 19 It can be seen that the third type of traveling wave tube (2-slit: wg=235μm, hg=120μm) has the widest bandwidth, with a 3-dB bandwidth of 22GHz (654~676GHz). The second type of traveling wave tube (0-slit: wg=247μm, hg=120μm) has a 3-dB bandwidth of 17GHz (661~678GHz). The first type of traveling wave tube (0-slit: wg=235μm, hg=210μm) has a 3-dB bandwidth of 3GHz (668~671GHz).

[0067] Figure 20 This is a comparison graph showing the output gain versus frequency relationship of the three types of traveling wave tubes in this embodiment. Figure 13It can be seen that when the frequency is 670GHz, the output gain of the three types of traveling wave tubes is as follows: the third type of traveling wave tube is greater than the second type, which is greater than the first type, and the third type of traveling wave tube has the widest bandwidth.

[0068] Although the illustrative specific embodiments of the present invention have been described above to enable those skilled in the art to understand the invention, it should be understood that the invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the invention as defined and determined by the appended claims, and all inventions utilizing the concept of the present invention are protected.

Claims

1. A slit-type staggered double-grating waveguide slow-wave structure, each single-period structure comprising a metal shell (1), an upper metal grating (2), and a lower metal grating (3), wherein the upper metal grating (2) and the lower metal grating (3) are staggered in a half-period manner, and a rectangular electron beam channel (4) exists between the upper metal grating (2) and the lower metal grating (3), characterized in that: Set at the lower edge of the upper metal grid (2) and the upper edge of the lower metal grid (3) respectively A rectangular prism notch (5), Each notch (5) has the same shape and size, and the width is... The range of values ​​is ,in This indicates the width of the upper metal grid (2) / lower metal grid (3), and the distance between the notches (5) in the upper metal grid (2) or lower metal grid (3). The range of values ​​is In a single-period structure, a coordinate system is constructed with the center of the electron beam channel (4) as the origin, the horizontal direction as the X-axis, the vertical direction as the Y-axis, and the electron beam direction as the Z-axis. The upper metal grid (2) or the lower metal grid (3)... The projections of the notches onto the XY plane are symmetrically distributed about the Y-axis, and the upper metal grid (2) The notch and the lower metal grille (3) The projections of the gaps onto the XY plane are symmetrical about the X-axis.

2. The slit-type staggered dual-grid waveguide slow-wave structure according to claim 1, characterized in that, The height of the gap (5) The range of values ​​is ,in Indicates the width of the gap.

3. The slit-type staggered dual-grid waveguide slow-wave structure according to claim 1, characterized in that, The number of gaps (5) .

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