阅读说明：本技术 一种适用于大功率行波管的宽带低通滤波器 (Broadband low-pass filter suitable for high-power travelling wave tube ) 是由 王建勋 代子豪 罗勇 于 2021-08-27 设计创作，主要内容包括：本发明公开了一种适用于大功率行波管的宽带低通滤波器,属于微波电子学及电真空技术领域。该滤波器包括主波导、对称设置于主波导两端的主波导匹配结构、分别设置于主波导宽边的两排耦合缝隙阵列、以及耦合缝隙另一端连接的高频匹配结构。在工作频带内,低频信号和高频信号同时通过主波导匹配结构进入主波导,由于耦合缝隙无法传输低频信号,因此低频信号通过主波导到达另一端的主波导匹配结构输出,而高频信号则通过耦合缝隙进入过渡连接段,最终进入高频匹配结构,被高频匹配结构末端的标准匹配负载吸收。由此达到了宽带低通滤波器中低通滤波的效果。(The invention discloses a broadband low-pass filter suitable for a high-power traveling wave tube, and belongs to the technical field of microwave electronics and electric vacuum. The filter comprises a main waveguide, main waveguide matching structures symmetrically arranged at two ends of the main waveguide, two rows of coupling slot arrays respectively arranged on the wide side of the main waveguide, and a high-frequency matching structure connected with the other ends of the coupling slots. In a working frequency band, a low-frequency signal and a high-frequency signal enter the main waveguide through the main waveguide matching structure at the same time, because the coupling gap can not transmit the low-frequency signal, the low-frequency signal reaches the main waveguide matching structure at the other end through the main waveguide to be output, and the high-frequency signal enters the transition connecting section through the coupling gap, finally enters the high-frequency matching structure and is absorbed by a standard matching load at the tail end of the high-frequency matching structure. Thereby achieving the effect of low-pass filtering in the broadband low-pass filter.)

1. A broadband low-pass filter suitable for a high-power traveling wave tube is characterized by comprising a main waveguide, main waveguide matching structures symmetrically arranged at two ends of the main waveguide, two rows of coupling slot arrays respectively arranged at the wide edge of the main waveguide, and a high-frequency matching structure;

the main waveguide is a rectangular waveguide, and the width dimension of the main waveguide is as follows: narrow side size 2: 1;

the main waveguide matching structure is used for matching and transitioning the standard rectangular waveguide to the main waveguide;

the row of coupling slot arrays comprises 5-10 coupling slots which are arranged periodically; the two rows of coupling slot arrays are arranged in a staggered manner for a half period along the axis direction;

the coupling gap is a stepped coupling gap with gradually changed width sides, and the other end of the coupling gap is connected with the high-frequency matching structure through a transition connecting section;

the high-frequency matching structure is a stepped waveguide structure formed by multiple sections of rectangular waveguides with gradually changed sizes, and the tail end of the stepped waveguide structure is loaded with a standard matching load.

2. The broadband low-pass filter applicable to high-power traveling-wave tubes according to claim 1, wherein the size of the wide side of the main waveguide ranges from 1 λ to 2 λ₁，λ₁The wavelength of the highest operating frequency.

3. The broadband low pass filter for high power traveling wave tubes according to claim 1, wherein the width dimension of the transition connection section is: narrow side size 1: 0.1-0.3, and the size of the wide side ranges from 0.4 to 0.6 lambda₂，λ₂The wavelength of the lowest frequency of the high frequency band.

4. The broadband low-pass filter applicable to high-power traveling-wave tubes according to claim 1, wherein the main waveguide matching structure is a stepped waveguide structure composed of multiple sections of rectangular waveguides with gradually changed sizes.

5. The broadband low-pass filter applicable to high-power traveling-wave tubes according to claim 3, wherein the transition connection section is a straight transition connection section or a bent transition connection section, and the straight transition connection section and the bent transition connection section are periodically arranged in a staggered manner.

6. The broadband low-pass filter applicable to high-power traveling-wave tubes according to claim 3, wherein the transition connection section is a straight transition connection section, a left-side bent transition connection section, or a right-side bent transition connection section, and the three transition connection sections are arranged in a periodically staggered manner.

7. A broadband low pass filter for high power traveling wave tubes according to claim 5 or 6, wherein the bend transition section is operated with a corner outer chamfer.

Technical Field

The invention belongs to the technical field of microwave electronics and electric vacuum, and particularly relates to a broadband low-pass filter suitable for a high-power traveling wave tube.

Background

With the increase of strategic demands of the country, the millimeter wave frequency band becomes a popular choice in the fields of next-generation communication and military. The electric vacuum device has great research significance in a millimeter wave frequency band due to the characteristics of excellent reliability and high power capacity. The traveling wave tube is used as one of the electro-vacuum devices, and is particularly suitable for the fields of electronic countermeasure, satellite-borne or airborne communication, radar and the like because of the characteristics of incomparable broadband and miniaturization of other devices. The latest research is that the band-shaped traveling wave tube has larger current and power capacity compared with the traditional cylindrical electron beam. Therefore, countries around the world strive to develop high-power and high-gain traveling-wave tubes to meet the requirements of scientific research fields.

If the oscillation signal is not processed, the output characteristic and the working performance of the traveling wave tube are seriously influenced. The traditional filtering structure of the waveguide system generally filters the oscillation signal by adding a resonant cavity, but the frequency band of the resonant cavity filter is often a narrow band or a spot frequency. Therefore, the traditional filtering structure cannot meet the treatment of the oscillation problem of the traveling wave tube.

Disclosure of Invention

The invention aims to provide a broadband low-pass filter suitable for a high-power traveling wave tube, so that the broadband low-pass filter can transmit low-frequency signals and absorb high-frequency signals in a 10-20GHz working frequency band.

The technical scheme of the invention is as follows:

the broadband low-pass filter is characterized by comprising a main waveguide, main waveguide matching structures symmetrically arranged at two ends of the main waveguide, two rows of coupling slot arrays respectively arranged on the wide side of the main waveguide, and a high-frequency matching structure.

The main waveguide is a rectangular waveguide, and the width dimension of the main waveguide is as follows: narrow side size 2: 1, the size of the wide side is in the range of 1-2 lambda₁，λ₁The wavelength of the highest operating frequency.

The main waveguide matching structure is used for matching and transferring the standard rectangular waveguide to the main waveguide.

The row of coupling slot arrays comprises 5-10 coupling slots which are arranged periodically; the two rows of coupling slot arrays are arranged in a staggered mode by a half period along the axis direction.

The coupling gap is a stepped coupling gap with gradually changed width sides, and the other end of the coupling gap is connected with the high-frequency matching structure through a transition connecting section.

The high-frequency matching structure is a stepped waveguide structure formed by multiple sections of rectangular waveguides with gradually changed sizes, and the tail end of the stepped waveguide structure is loaded with a standard matching load.

Further, the broadside dimension of the transition connecting section is as follows: narrow side size 1: 0.1-0.3, and the size of the wide side ranges from 0.4 to 0.6 lambda₂，λ₂The wavelength of the lowest frequency of the high frequency band.

Furthermore, the main waveguide matching structure is a stepped waveguide structure formed by multiple sections of rectangular waveguides with gradually changed sizes.

Furthermore, the transition connecting section is a straight transition connecting section or a bending transition connecting section, and the straight transition connecting section and the bending transition connecting section are arranged in a periodic staggered mode.

Furthermore, the transition connecting section is a straight transition connecting section, or a left-side bent transition connecting section, or a right-side bent transition connecting section, and the three transition connecting sections are arranged in a periodically staggered manner.

Further, the bending angle outside corner cutting operation of the bending transition connecting section.

In the working frequency band, the low-frequency signal and the high-frequency signal enter the main waveguide through the main waveguide matching structure simultaneously. Because the coupling gap can not transmit low-frequency signals, the low-frequency signals reach the main waveguide matching structure at the other end through the main waveguide to be output, and the high-frequency signals enter the transition connecting section through the coupling gap, finally enter the high-frequency matching structure and are absorbed by the standard matching load at the tail end of the high-frequency matching structure. Thereby achieving the effect of low-pass filtering in the broadband low-pass filter.

Drawings

FIG. 1 is a schematic diagram of an overall structure of a broadband low-pass filter according to an embodiment;

FIG. 2 is a front view of a wideband low pass filter of an embodiment;

FIG. 3 is a side view of a broadband low pass filter of an embodiment;

FIG. 4 is a diagram of a coupling slot and a high frequency structure branch of the broadband low pass filter according to the embodiment;

fig. 5 is a graph of performance parameters for this example.

Detailed Description

The invention is further illustrated below with reference to the figures and examples.

The embodiment provides a broadband low-pass filter suitable for a Ka-band strip-shaped traveling wave tube.

Referring to fig. 1, the filter includes a main waveguide (1), main waveguide matching structures (2) symmetrically disposed at two ends of the main waveguide, two rows of coupling slot arrays (3) respectively disposed at wide sides of the main waveguide, a transition connection section (4), a high-frequency matching structure (5), and a Ka standard matching load (6).

The total length lg of the filter is 105 mm.

The main waveguide is a rectangular waveguide, the size of the wide side of the main waveguide is 8mm, and the size of the narrow side of the main waveguide is 4 mm.

The main waveguide matching structure is used for matching and transitioning a standard rectangular waveguide to the main waveguide (1). The main waveguide matching structure (2) is divided into three sections (2-1, 2-2 and 2-3), the wide sides of the main waveguide matching structure are 7.112mm, 7.3mm and 7.6mm in sequence, the narrow sides of the main waveguide matching structure are 3.556mm, 3.65mm and 3.8mm in sequence, and the lengths of the main waveguide matching structure are d 1-3 mm, d 2-3.3 mm and d 3-3 mm in sequence.

The row of coupling slit arrays comprises 8 periodically arranged coupling slits (3); two rows of coupling slot arrays are staggered in the axial direction by half a period, and the length d of one period is 6.8 mm.

The coupling gap is a stepped coupling gap (3) with gradually changed wide edges, the narrow edge of the coupling gap is 0.6mm, the width of three steps is w 4-8 mm, w 5-6.8 mm, w 6-4.4 mm, the height of the three steps is d 4-3 mm, d 5-1.4 mm and d 6-5.6 mm, and the other end of the coupling gap is connected with the high-frequency matching structure through a transition connecting section.

The transitional coupling section comprises a right-side bent transitional coupling section (4-1), a left-side bent transitional coupling section (4-2) and a straight transitional coupling section (4-3), the three transitional coupling sections are periodically arranged in a staggered mode, the wide side size of the transitional coupling section (4) is 4.4mm, the narrow side size of the transitional coupling section is 0.6mm, the turning angle of the bent transitional coupling section is 90 degrees, and the outer side corner cut operation is performed. The purpose of arranging the bending transition connecting section is to facilitate the connection of a Ka standard matching load (6) with a rear-stage device.

The high-frequency matching structure (5) is a step type waveguide structure consisting of 4 sections of rectangular waveguides with gradually changed sizes, and the tail end of the high-frequency matching structure is loaded with a Ka standard matching load (6). The ladder-type waveguide structure is divided into four sections of 5-1, 5-2, 5-3 and 5-4, the wide sides of the ladder-type waveguide structure are sequentially 4.43mm, 5.34mm, 6.65mm and 7.112mm, the narrow sides of the ladder-type waveguide structure are sequentially 0.72mm, 1.64mm, 3mm and 3.556mm, and the lengths of the ladder-type waveguide structure are sequentially 3.57mm, 2.63mm, 2.68mm and 13 mm.

The working frequency band of the filter of the embodiment is 26GHz-40GHz and the filter works in TE₁₀Mode(s). FIG. 5 is a graph of performance parameters for this example, S11 being the reflection coefficient of the filter, S11 being less than-20 dB in both 26-40 GHz; s21 is the transmission coefficient of the filter, S21 is more than-0.1 dB in 26-33GHz and less than-10 dB in 35-39 GHz; the invention can realize low-frequency transmission and high-frequency absorption in the working frequency band, and simultaneously keep the reflection less than-20 dB in the full frequency band.

The above examples are only for convenience of explaining the present invention, and the broadband low-pass filter suitable for the high-power traveling wave tube provided by the present invention can be used for ribbon traveling wave tubes of different frequency bands. The invention belongs to the protection scope by changing various parameters mentioned in the scheme of the invention and using the structure of the invention.