A staggered double-grating ridge waveguide slow-wave structure

Abstract

The present invention discloses a staggered double-grid ridge waveguide slow-wave structure, comprising a metal shell, a row of upper metal grids, a row of lower metal grids and an electron injection channel; the upper metal grids and the lower metal grids are both rectangular metal grids, a row of upper metal grids is arranged at the inner top of the metal shell, a row of lower metal grids is arranged at the inner bottom of the metal shell, and the upper metal grids and the lower metal grids are not in contact with the side walls of the metal shell, and an electron injection channel is arranged between the row of upper metal grids and the row of lower metal grids; the row of upper metal grids and the row of lower metal grids are arranged periodically, and the period of the row of upper metal grids and the row of lower metal grids is staggered. The present application improves the coupling impedance of the slow-wave structure, is more conducive to the initiation of backward wave oscillation and the energy interaction between the electromagnetic field and the electron beam, has a lower low-end cutoff frequency than the conventional staggered double-grid structure, and has a larger cold passband bandwidth, so it can have a wider tuning voltage range to achieve ultra-wideband characteristics.

Description

Technical Field

[0001] The invention belongs to the field of microwave electric vacuum technology, and in particular relates to an interlaced double-grid ridge waveguide slow-wave structure. Background Art

[0002] Terahertz waves are electromagnetic waves with frequencies between microwave and infrared bands. Terahertz electromagnetic waves have important research value and broad application prospects in the fields of space communication, ultra-high resolution weapon guidance, medical imaging, security inspection and material testing. Vacuum electronic devices are devices that realize the interaction between electron energy and electromagnetic wave energy in a vacuum state. Among them, the device that uses the electron beam to interact with the microwave signal transmitted in the slow-wave structure and continuously transfers the kinetic energy of the electron beam to the microwave signal field in the slow-wave structure so that the signal is amplified is called a traveling wave tube. If there is no input signal and input coupler, the device that generates electromagnetic waves of a specific frequency by self-excited oscillation of the electron beam is called a backward wave oscillator. For the slow-wave structure of the backward wave oscillator, it is required not only to have abnormal dispersion characteristics, but also to have negative dispersion. Therefore, as the core device in the backward wave oscillator, the slow-wave structure directly determines the performance of the backward wave oscillator. At present, the slow-wave structures widely used in the backward wave oscillator include rectangular staggered double gratings and folded waveguides.

[0003] In order to further meet the development requirements of terahertz band devices for high frequency, high power and wide bandwidth, the present application proposes an interlaced double-gate ridge waveguide slow-wave structure with broadband and high coupling impedance characteristics. Summary of the invention

[0004] The purpose of the present application is to provide an interleaved double-gate ridge waveguide slow-wave structure, which improves the coupling impedance and, when applied to a backward wave oscillator, has higher output power and wider operating bandwidth than the existing conventional interleaved double-gate slow-wave structure.

[0005] The present invention is achieved through the following technical solutions:

[0006] A staggered double-grid ridge waveguide slow-wave structure comprises a metal shell, a row of upper metal grids, a row of lower metal grids and an electron injection channel;

[0007] A row of upper metal grids is arranged at the inner top end of the metal shell, and a row of lower metal grids is arranged at the inner bottom end of the metal shell, and the upper metal grids and the lower metal grids are not in contact with the side wall of the metal shell; a gap is arranged between a row of upper metal grids and a row of lower metal grids to form a rectangular electron injection channel, or a gap is arranged between a row of upper metal grids and a row of lower metal grids, and arc notches are arranged on the upper metal grids and the lower metal grids, and the arc notches on the upper metal grids and the arc notches on the lower metal grids are both arcs on the same cylinder to form a cylindrical electron injection channel, and a row of upper metal grids and a row of lower metal grids are arranged in a staggered structure to form a staggered double grid.

[0008] In a possible implementation, the metal shell is a rectangular body, and a penetrating rectangular channel is provided on the metal shell, the row of upper metal grids, the row of lower metal grids and the electron injection channel are all provided in the rectangular channel, and the electron injection channel is parallel to the rectangular channel.

[0009] In a possible implementation manner, a row of the upper metal gates and a row of the lower metal gates are staggered by half a period.

[0010] In a possible implementation manner, the thickness of the upper metal grid along the electron injection channel direction is 0.25p, where p represents the period of a row of the upper metal grid.

[0011] In a possible implementation manner, a distance between any two adjacent upper metal gates is 0.75p.

[0012] In a possible implementation, the spacing between the upper metal grid and two sides of the metal shell is / 2, wherein a represents the width of the rectangular channel, and L represents the width of the upper metal grid in a direction perpendicular to the electron injection channel.

[0013] In a possible implementation manner, the thickness of the lower metal grid along the electron injection channel direction is 0.25p, where p represents the period of a row of the lower metal grid.

[0014] In a possible implementation manner, a distance between any two adjacent lower metal gates is 0.75p.

[0015] In a possible implementation, the spacing between the lower metal grid and both sides of the metal shell is / 2, wherein a represents the width of the rectangular channel, and L represents the width of the upper metal grid in a direction perpendicular to the electron injection channel.

[0016] The present application provides an interlaced double-gate ridge waveguide slow-wave structure, in which the interlaced double gates are concentrated at the double ridges of the ridge waveguide, so that the high-frequency electric field is more concentrated on the top of the metal gate, that is, the position of the electron beam channel, so that the coupling impedance of the slow-wave structure is improved, which is more conducive to the initiation of backward wave oscillation and the energy interaction between the electromagnetic field and the electron beam. The low-end cutoff frequency is lower than that of the conventional interlaced double-gate structure, and the cold passband bandwidth is increased, so that a wider tuning voltage range can be achieved to achieve ultra-wideband characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0018] Figure 1 A schematic structural diagram of an interlaced double-grating ridge waveguide slow-wave structure when the electron injection channel provided in an embodiment of the present application is a rectangular channel.

[0019] Figure 2 A schematic structural diagram of an interlaced double-grating ridge waveguide slow-wave structure when the electron injection channel provided in an embodiment of the present application is a circular channel.

[0020] Figure 3 A schematic longitudinal section diagram of a staggered double-gate ridge waveguide slow-wave structure provided in an embodiment of the present application.

[0021] Figure 4 A schematic cross-sectional view of a staggered double-grating ridge waveguide slow-wave structure provided in an embodiment of the present application.

[0022] Figure 5 This is a comparison diagram of the dispersion curves of the staggered double-gate ridge waveguide slow-wave structure provided in an embodiment of the present application and the conventional staggered double-gate slow-wave structure.

[0023] Figure 6 A comparison diagram of the coupling impedance of the staggered double-gate ridge waveguide slow-wave structure provided in an embodiment of the present application and the conventional staggered double-gate slow-wave structure.

[0024] Figure 7 A top view of the longitudinal electric field of a conventional staggered double-gate slow-wave structure provided in an embodiment of the present application.

[0025] Figure 8 A top view of the longitudinal electric field of the staggered double-gate ridge waveguide slow-wave structure provided in an embodiment of the present application.

[0026] Fig. 9 A side view of the longitudinal electric field of a conventional staggered double-gate slow-wave structure provided in an embodiment of the present application.

[0027] Fig.10 A side view of the longitudinal electric field of the staggered double-gate ridge waveguide slow-wave structure provided in an embodiment of the present application.

[0028] Marks and corresponding parts names in the attached drawings:

[0029] 1-metal shell, 2-upper metal grid, 3-lower metal grid, 4-electron injection channel. DETAILED DESCRIPTION

[0030] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention. Example

[0031] In order to further broaden the bandwidth of the existing staggered double-gate slow-wave structure and improve the coupling impedance, the embodiment of the present application proposes a staggered double-gate ridge waveguide slow-wave structure with ultra-wide bandwidth and high coupling impedance. When it is applied to a backward wave oscillator, it can have higher output power and wider operating bandwidth than the existing conventional staggered double-gate slow-wave structure.

[0032] like Figure 1 and Figure 2 As shown together, an embodiment of the present application provides an interlaced double-gate ridge waveguide slow-wave structure, including a metal shell 1, a row of upper metal gates 2, a row of lower metal gates 3 and an electron injection channel 4; the upper metal gates 2 and the lower metal gates 3 can both be rectangular metal gates, trapezoidal metal gates or gate bodies of other shapes. A row of upper metal grids 2 is arranged at the inner top end of the metal shell 1, and a row of lower metal grids 3 is arranged at the inner bottom end of the metal shell 1, and the upper metal grids 2 and the lower metal grids 3 are not in contact with the side wall of the metal shell 1; a gap is arranged between a row of upper metal grids 2 and a row of lower metal grids 3 to form a rectangular electron injection channel 4, or a gap is arranged between a row of upper metal grids 2 and a row of lower metal grids 3, and arc notches are arranged on the upper metal grids 2 and the lower metal grids 3, and the arc notches on the upper metal grids 2 and the arc notches on the lower metal grids 3 are both arcs on the same cylinder to form a cylindrical electron injection channel 4, and the electron injection channel 4 can also be set to other shapes, and a row of upper metal grids 2 and a row of lower metal grids 3 are arranged in a staggered structure to form a staggered double grid.

[0033] When a row of upper metal grids 2 is disposed at the inner top of the metal shell 1, and a row of lower metal grids 3 is disposed at the inner bottom of the metal shell 1, the row of upper metal grids 2 should be directly opposite to the row of lower metal grids 3, and the two are only staggered in period. It is worth noting that the period between a row of upper metal grids 2 and a row of lower metal grids 3 should be the same, that is, the spacing between any two adjacent upper metal grids 2 and the spacing between any two adjacent lower metal grids 3 should be the same.

[0034] The staggered double-grid ridge waveguide slow-wave structure provided in the present application is easy to process, has a large interaction area, has good heat dissipation capability, can withstand higher power, and has the advantages of wide operating bandwidth and concentrated electric field.

[0035] For example: the height of the upper metal grid 2 and the lower metal grid 3 are both h=0.05mm (i.e., perpendicular to the top of the metal shell 1 or perpendicular to the edge of the bottom of the metal shell 1), the width of the upper metal grid 2 and the lower metal grid 3 are both L=0.09mm (i.e., parallel to the top of the metal shell 1 and perpendicular to the edge of the electron injection channel 4), then the electron injection channel 4 is perpendicular to the rectangular surface formed by h and L, the thickness of the upper metal grid 2 and the lower metal grid 3 along the electron injection channel 4 (i.e., the length of the upper metal grid 2 and the lower metal grid 3, which is parallel to the electron injection channel 4) can be g=0.25*0.055mm, and a row of upper metal grids 2 are arranged at equal intervals (i.e., the spacing between any two adjacent upper metal grids 2 can be 0.75*0.055mm), a row of lower metal grids 3 are arranged at equal intervals (i.e., the spacing between any two adjacent lower metal grids 3 can be 0.75*0.055mm), and the upper metal grid 2 and the lower metal grid 3 can be staggered, thereby forming an interlaced double-gate ridge waveguide slow-wave structure.

[0036] In a possible implementation, the metal shell 1 is a rectangular body, and a penetrating rectangular channel is provided on the metal shell 1, a row of upper metal grids 2, a row of lower metal grids 3 and an electron injection channel 4 are all provided in the rectangular channel, and the electron injection channel 4 is parallel to the rectangular channel.

[0037] like Figure 3 The longitudinal section diagram of the staggered double-grating ridge waveguide slow-wave structure provided and Figure 4 The cross-sectional schematic diagram of the provided staggered double-gate ridge waveguide slow-wave structure is shown together, the width of the rectangular channel is a (i.e., the wide side dimension of the waveguide), the height of the rectangular channel is z (i.e., the narrow side dimension of the waveguide), the width of the upper metal gate 2 and the lower metal gate 3 along the width direction of the rectangular channel is L, the height of the upper metal gate 2 and the lower metal gate 3 along the height direction of the rectangular channel is h, the height of the electron injection channel is 2b, then z=2b+2h.

[0038] In a possible implementation manner, a row of upper metal grids 2 and a row of lower metal grids 3 are staggered by half a period.

[0039] Optionally, the period of a row of upper metal gates 2 and the period of a row of lower metal gates 3 can be staggered by other values, for example, the period of a row of upper metal gates 2 and the period of a row of lower metal gates 3 are staggered by 0.3 period, 0.6 period or 0.8 period, etc. In the embodiment of the present application, the preferred choice is to stagger a row of upper metal gates 2 and a row of lower metal gates 3 by half a period.

[0040] In a possible implementation manner, a thickness g of the upper metal grid 2 along the direction of the electron injection channel 4 is 0.25p, where p represents a period of a row of the upper metal grid 2 .

[0041] In a possible implementation manner, the distance between any two adjacent upper metal gates 2 is 0.75p.

[0042] Optionally, the thickness g of the upper metal grid 2 along the direction of the electron injection channel 4 may also be other values, for example, the thickness g of the upper metal grid 2 along the direction of the electron injection channel 4 may be 0.2p, 0.3p or other values, but when the thickness g of the upper metal grid 2 along the direction of the electron injection channel 4 changes, the spacing between any two adjacent upper metal grids 2 should also change, that is, one period should include the thickness of the upper metal grid 2 and the spacing between adjacent upper metal grids 2. A preferred choice in this embodiment is that the spacing between any two adjacent upper metal grids 2 is 0.75p, and the thickness g of the upper metal grid 2 along the direction of the electron injection channel 4 is 0.25p.

[0043] In a possible implementation, the spacing between the upper metal grid 2 and both sides of the metal shell 1 is (aL) / 2, where a represents the width of the rectangular channel, and L represents the width of the upper metal grid 2 in a direction perpendicular to the electron injection channel 4 .

[0044] Optionally, when the spacing between the upper metal grid 2 and the two sides inside the metal shell 1 is (aL) / 2, it means that a row of upper metal grids 2 is arranged in the middle position of the top surface inside the metal shell 1. The spacing between the upper metal grid 2 and the two sides inside the metal shell 1 can also be set to other values. For example, the spacing between the upper metal grid 2 and the two sides inside the metal shell 1 can be A and B respectively, A may not be equal to B, but A+B=(aL). In this embodiment, the preferred choice is that the spacing between the upper metal grid 2 and the two sides inside the metal shell 1 is (aL) / 2.

[0045] In a possible implementation manner, a thickness g of the lower metal grid 3 along the electron injection channel 4 is 0.25p, where p represents a period of a row of the lower metal grid 3 .

[0046] In a possible implementation manner, the distance between any two adjacent lower metal gates 3 is 0.75p.

[0047] Optionally, the thickness g of the lower metal grid 3 along the direction of the electron injection channel 4 can also be other values, for example, the thickness g of the lower metal grid 3 along the direction of the electron injection channel 4 can be 0.2p, 0.3p or other values, but when the thickness g of the lower metal grid 3 along the direction of the electron injection channel 4 changes, the spacing between any two adjacent lower metal grids 3 should also change, that is, one period should include the thickness of the lower metal grid 3 and the spacing between adjacent lower metal grids 3. A preferred choice in this embodiment is that the spacing between any two adjacent lower metal grids 3 is 0.75p, and the thickness g of the lower metal grid 3 along the direction of the electron injection channel 4 is 0.25p.

[0048] In a possible implementation, the spacing between the lower metal grid 3 and both sides of the metal shell 1 is (aL) / 2, where a represents the width of the rectangular channel, and L represents the width of the upper metal grid 2 in a direction perpendicular to the electron injection channel 4 .

[0049] Optionally, when the spacing between the lower metal grid 3 and the two sides inside the metal shell 1 is (aL) / 2, it means that a row of lower metal grids 3 is arranged in the middle position of the bottom surface inside the metal shell 1. The spacing between the lower metal grid 3 and the two sides inside the metal shell 1 can also be set to other values. For example, the spacing between the lower metal grid 3 and the two sides inside the metal shell 1 can be A and B respectively, A may not be equal to B, but A+B=(aL). In this embodiment, the preferred choice is that the spacing between the lower metal grid 3 and the two sides inside the metal shell 1 is (aL) / 2.

[0050] Optionally, in the 1 THz frequency band, an embodiment of the present application provides an interlaced double-gate ridge waveguide slow-wave structure with structural dimensions of: a=0.180 mm, b=0.0125 mm, h=0.05 mm, L=0.09 mm, and p=0.055 mm.

[0051] The present application provides an interlaced double-gate ridge waveguide slow-wave structure, in which the interlaced double gates are concentrated at the double ridges of the ridge waveguide, so that the high-frequency electric field is more concentrated on the top of the metal gate, that is, the position of the electron beam channel, so that the coupling impedance of the slow-wave structure is improved, which is more conducive to the initiation of backward wave oscillation and the energy interaction between the electromagnetic field and the electron beam. The low-end cutoff frequency is lower than that of the conventional interlaced double-gate structure, and the cold passband bandwidth is increased, so that a wider tuning voltage range can be achieved to achieve ultra-wideband characteristics.

[0052] The dispersion curve is obtained by calculation using the three-dimensional electromagnetic simulation software CST. Figure 5A dispersion curve comparison diagram of an interlaced double-gate ridge waveguide slow-wave structure and a conventional interlaced double-gate waveguide provided in an embodiment of the present application shows that when the high-end cut-off frequencies of the two are equivalent, the low-end cut-off frequency of the present application is 240 GHz lower than that of the conventional interlaced double-gate slow-wave structure, that is, the cold passband bandwidth of the present application is 675 GHz, while the cold passband bandwidth of the conventional interlaced double-gate waveguide is 435 GHz. The former is relatively wider than the latter by about 55%.

[0053] Figure 6 This is a comparison chart of the coupling impedance of the staggered double-grid ridge waveguide of the present application and the conventional staggered double-grid slow-wave structure. In the range of about 750GHz to 1150GHz, the coupling impedance of the present application is higher than that of the conventional staggered double-grid waveguide, up to about 22%. This means that using the staggered double-grid ridge waveguide of the present application as a backward waveguide can obtain higher output power and interaction efficiency than the staggered double-grid slow-wave structure.

[0054] Figure 7 and Figure 8 The electric field top views of the conventional staggered double-gate slow-wave structure and the staggered double-gate ridge waveguide slow-wave structure provided in the present application are respectively shown. In comparison, the electric field at the metal ridge position of the latter is more concentrated, and this happens to be the position where the electron beam passes through, which is why the coupling impedance of the structure is larger.

[0055] Fig. 9 and Fig.10 These are side views of the electric field of a conventional staggered double-gate slow-wave structure and a staggered double-gate ridge waveguide slow-wave structure. From this angle, it can be seen that the longitudinal component of the electric field between two adjacent metal gates of the staggered double-gate ridge waveguide is significantly more concentrated and enhanced, which further explains why this structure can further improve the coupling impedance compared to the conventional staggered double-gate slow-wave structure.

[0056] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the following claims.

[0057] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A staggered double-grid ridge waveguide slow-wave structure, characterized in that: It comprises a metal shell (1), a row of upper metal grids (2), a row of lower metal grids (3) and an electron injection channel (4); A row of upper metal grids (2) is arranged at the top end of the metal shell (1), and a row of lower metal grids (3) is arranged at the bottom end of the metal shell (1), and the upper metal grids (2) and the lower metal grids (3) are not in contact with the side wall of the metal shell (1); a gap is arranged between the row of upper metal grids (2) and the row of lower metal grids (3) to form a rectangular electron injection channel (4); or a gap is arranged between the row of upper metal grids (2) and the row of lower metal grids (3), and arc notches are arranged on the upper metal grids (2) and the lower metal grids (3), and the arc notches on the upper metal grids (2) and the arc notches on the lower metal grids (3) are both arcs on the same cylinder to form a cylindrical electron injection channel (4), and the row of upper metal grids (2) and the row of lower metal grids (3) are arranged in a staggered structure to form a staggered double grid; Wherein, the thickness of the upper metal grid (2) and the lower metal grid (3) along the direction of the electron injection channel (4) is g.

2. The staggered double-gate ridge waveguide slow-wave structure according to claim 1, characterized in that: The metal shell (1) is a rectangular body, and a penetrating rectangular channel is provided on the metal shell (1); the row of upper metal grids (2), the row of lower metal grids (3) and the electron injection channel (4) are all arranged in the rectangular channel, and the electron injection channel (4) is parallel to the rectangular channel.

3. The staggered double-gate ridge waveguide slow-wave structure according to claim 1, characterized in that: A row of the upper metal grids (2) and a row of the lower metal grids (3) are staggered by half a period.

4. The staggered double-gate ridge waveguide slow-wave structure according to claim 1, characterized in that: The thickness of the upper metal grid (2) along the direction of the electron injection channel (4) is 0.25p, wherein p represents the period of a row of the upper metal grid (2).

5. The staggered double-grid ridge waveguide slow-wave structure according to claim 4, characterized in that: The distance between any two adjacent upper metal gates (2) is 0.75p.

6. The staggered double-gate ridge waveguide slow-wave structure according to claim 2, characterized in that: The distances between the upper metal grid (2) and the two sides inside the metal shell (1) are both (aL) / 2, wherein a represents the width of the rectangular channel, and L represents the width of the upper metal grid (2) in a direction perpendicular to the electron injection channel (4).

7. The staggered double-gate ridge waveguide slow-wave structure according to claim 1, characterized in that: The thickness of the lower metal grid (3) along the direction of the electron injection channel (4) is 0.25p, wherein p represents the period of a row of the lower metal grid (3).

8. The staggered double-gate ridge waveguide slow-wave structure according to claim 7, characterized in that: The distance between any two adjacent lower metal grids (3) is 0.75p.

9. The staggered double-gate ridge waveguide slow-wave structure according to claim 2, characterized in that: The spacing between the lower metal grid (3) and the two sides inside the metal shell (1) is (aL) / 2, wherein a represents the width of the rectangular channel, and L represents the width of the upper metal grid (2) in a direction perpendicular to the electron injection channel (4).

Images