CN111029704A

CN111029704A - Compact waveguide bidirectional coupler

Info

Publication number: CN111029704A
Application number: CN201911301815.2A
Authority: CN
Inventors: 王清源; 何敏
Original assignee: University of Electronic Science and Technology of China
Current assignee: University of Electronic Science and Technology of China
Priority date: 2019-12-17
Filing date: 2019-12-17
Publication date: 2020-04-17

Abstract

The invention discloses a compact waveguide bidirectional coupler which comprises a rectangular waveguide tube, two coupling holes, a coupling cavity and two coaxial connectors, wherein the two coupling holes are positioned on one or two H surfaces of the waveguide tube along the Y direction and are communicated with the waveguide tube, the coupling cavity is positioned near each coupling hole and is communicated with the coupling hole, the coupling conductor is positioned in each coupling cavity, and the inner conductor extends into each coupling cavity and is respectively communicated with two ends of the coupling conductor. By adopting the waveguide section as the waveguide tube, the manufacturing cost is obviously reduced; the two sets of coupling structures are arranged in a flush mode in the axial direction of the waveguide, so that the length of the device is shortened remarkably; the power capacity of the device is greatly improved by arranging the coupling structure to deviate from the center of the wide edge of the waveguide. The device also has flat coupling coefficient frequency response and high directivity coefficient, and can be widely applied to the fields of radar, missile guidance, communication, microwave heating and the like.

Description

Compact waveguide bidirectional coupler

Technical Field

The invention relates to a compact waveguide bidirectional coupler. In particular to a compact high-power waveguide bidirectional directional coupler.

Background

High power microwave systems often employ waveguides as transmission lines to deliver microwave energy, but often result in reflection of the energy due to load mismatch. Not only will this mismatch significantly reduce the efficiency of the system, but the reverse transmission of reflected energy to the microwave source may affect the operational stability of the microwave source or even burn the source. Therefore, between the microwave source and the load, it is often necessary to add a waveguide tuner and a waveguide directional coupler. By changing the insertion depth of the pins of the waveguide tuner and respectively coupling microwave energy in the forward direction and the reverse direction from the waveguide directional coupler, good matching of the microwave system can be realized. Therefore, the waveguide directional coupler is widely applied to the deployment of microwave systems.

In order to monitor microwave energy in both directions, a waveguide bidirectional directional coupler is required. The conventional coupled loop waveguide directional coupler adopts a coupling ring structure to simultaneously couple out microwave energy in two directions. But the directivity of the directional coupler is affected due to the poor matching of the adopted detectors. For this reason, conventional waveguide bidirectional directional couplers often employ two coupling ring structures. The device is provided with two sets of coupling structures on the H surface of the waveguide along the central line. This structure has two problems: first, the increased length of the conventional waveguide bidirectional directional coupler results in difficulty in installation and inconvenience in use thereof, as well as waste of materials and an increase in manufacturing costs. Also, the electric field intensity at the lateral center of the H-plane of the waveguide is the largest for the fundamental mode operating mode TE10 mode. Opening the coupling hole in the lateral center of the H-plane of the waveguide will result in a reduced power capacity of the waveguide bidirectional directional coupler.

Disclosure of Invention

The invention aims to provide a compact waveguide bidirectional coupler. In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a compact waveguide bidirectional coupler comprises a rectangular waveguide tube, two coupling holes, a coupling cavity and two coaxial connectors, wherein the axis of the rectangular waveguide tube is wide along the Z direction and along the X direction, the two coupling holes are positioned on one or two H surfaces of the waveguide tube along the Y direction and are communicated with the waveguide tube, the coupling cavity is positioned near each coupling hole and is communicated with the coupling hole, the coupling conductor is positioned in each coupling cavity, and the inner conductor extends into each coupling cavity and is respectively communicated with two ends of the coupling conductor in the coupling cavity; the coupling conductor is not connected with the inner wall of the coupling cavity; the X, Y and Z directions form a rectangular coordinate system.

In order to save manufacturing costs, the two coupling holes are located on the same H-plane of the waveguide.

The two coupling holes of the traditional waveguide bidirectional directional coupler are staggered along the axis of the waveguide, so that the total length of the device is larger. In order to shorten the total length of the compact waveguide bidirectional coupler as much as possible, the center lines of the two coupling holes in the Y direction are aligned in the Z direction.

Both coupling holes of the conventional waveguide bidirectional directional coupler are disposed at a laterally central position in the X direction of the H-plane of the waveguide. The mode of operation in the rectangular waveguide is the TE10 mode, and this arrangement locates the coupling hole at the place where the electric field strength is strongest, resulting in a significant reduction in the power capacity of the device. In order to increase the power capacity of the device, in the present invention, the center lines of the two coupling holes in the Y direction are offset from the lateral center position of the waveguide in the X direction by a certain distance. The distance is at least 0.05 times the operating wavelength of free space.

The manufacture of the traditional waveguide bidirectional directional coupler is usually finished by milling from a bulk metal body. The waveguide tube is processed by adopting a standard waveguide section, so that the processing time is obviously shortened, the material loss is reduced, and the manufacturing cost is greatly reduced.

In another embodiment, the two coupling holes 2 may also be respectively disposed on two different H-planes of the waveguide tube along the Y-direction.

In order to obtain a relatively high directivity and to realize an accurate coupling coefficient with a small change with frequency, the two coupling holes are shaped like a cylinder whose axis is along the Y direction and whose cross section is rectangular.

In a preferred form, the coupling hole is shaped as a rectangular parallelepiped, and a long side thereof is parallel to an axial direction of the waveguide tube.

Meanwhile, the coupling cavity is in a cuboid shape, and the long edge of the coupling cavity is parallel to the axis direction of the waveguide tube.

The coupling conductor is shaped like a rectangular parallelepiped, and the long side thereof is parallel to the axial direction of the waveguide.

In a preferred design, the compact waveguide bi-directional coupler is a mirror symmetric structure with respect to the YZ plane.

The invention provides a compact waveguide bidirectional coupler. By arranging the two coupling holes at positions flush with each other in the axial direction of the waveguide in the Z-axis direction, the length of the device is greatly shortened. By offsetting the coupling aperture from the center of the broadside of the waveguide, the power capability of the device is significantly improved.

Drawings

FIG. 1 is a schematic top view of the invention and example 1

FIG. 2 is a cross-sectional view along AA of FIG. 1

Fig. 3 is a plot of the calculated coupling coefficient (in dB) for example 1.

Fig. 4 is a calculated directivity (in dB) curve for example 1.

Fig. 5 is a schematic top view of embodiment 2.

Fig. 6 is a cross-sectional view along AA of fig. 5.

Fig. 7 is a schematic top view of embodiment example 3.

Fig. 8 is a schematic top view of embodiment example 4.

Fig. 9 is a schematic top view of embodiment example 5.

The reference numbers in the drawings correspond to the names: 1-waveguide tube, 2-coupling hole, 3-coupling cavity, 4-coupling conductor and 5-coaxial connector.

Detailed Description

Examples 1

As shown in fig. 1-4.

A compact waveguide bidirectional coupler comprises a rectangular waveguide tube 1, two coupling holes 2 which are positioned on the upper H surface of the waveguide tube 1 and communicated with the waveguide tube 1, a coupling cavity 3 which is positioned near each coupling hole and communicated with the coupling hole, a coupling conductor 4 positioned in each coupling cavity 3, and 4 coaxial connectors 5 in total. The inner conductor of the coaxial connector extends into each coupling cavity 3 and is respectively communicated with one end of the coupling conductor 4. The coupling conductor 4 is not connected to the inner wall of the coupling cavity 3.

The two coupling holes 2 are flush in the Z-direction.

The center lines of the two coupling holes 2 in the Y direction are offset from the lateral center position of the waveguide 1 in the X direction by a certain distance. The distance is greater than 0.05 times the operating wavelength of free space

The waveguide tube is processed by adopting a BJ26 standard waveguide section bar.

The shape of coupling hole 2 is the cuboid, and its long limit is parallel with the axis direction of waveguide 1.

Meanwhile, the coupling cavity 3 is a cuboid, and the long side of the coupling cavity is parallel to the axial direction of the waveguide tube 1.

The coupling conductor 4 is shaped like a rectangular parallelepiped, and its long side is parallel to the axial direction of the waveguide 1.

The compact waveguide bi-directional coupler is of a mirror symmetry structure relative to a YZ plane.

Fig. 3 and 4 are calculated coupling coefficient curves and directivity curves of embodiment 1. The internal lateral dimension of the adopted BJ26 standard waveguide is 86.36 mm 43.18 mm, and the working bandwidth covers 2.17 GHz-3.3 GHz. As can be seen in FIG. 3, the coupling coefficient of the device is 58+/-1dB and the directivity is greater than 21.7dB over the entire operating bandwidth. The three-dimensional electromagnetic field simulation of the device shows that the power capacity of the device is improved by more than 100% compared with the traditional waveguide bidirectional directional coupler because the coupling hole deviates from the central position of the waveguide tube along the X direction.

EXAMPLES example 2

As shown in fig. 5 and 6

Embodiment 2 is different from embodiment 1 only in that two coupling holes and other portions of the coupling structure are respectively provided on two different H-planes, i.e., upper and lower H-planes, of the waveguide 1.

EXAMPLE 3

As shown in fig. 7

Embodiment 3 is different from embodiment 2 only in that two coupling holes and other portions of the coupling structure are provided at the lateral center of the waveguide 1 in the X direction. At the same time, both coupling holes and the rest of the coupling structure are rotated 8 degrees in the Y-direction. This embodiment can be made shorter than the conventional waveguide bidirectional directional coupler and embodiment 2.

EXAMPLE 4

As shown in fig. 8

Embodiment 4 differs from embodiment 1 only in that the two coupling holes and the other part of the coupling structure are rotated by 10 degrees about the Y-axis. This embodiment example can be made shorter than embodiment example 1.

EXAMPLE 5

As shown in fig. 9

Embodiment 4 differs from embodiment 4 only in that the two coupling holes and the other part of the coupling structure are rotated by 10 degrees and-10 degrees, respectively, with respect to their center lines along the Y-axis. This embodiment example is mirror symmetric with respect to the YZ plane.

An embodiment of the present invention is given above. The actual implementation is far more extensive than listed here. The compact waveguide bidirectional coupler is generally processed by a numerical control milling machine. To facilitate the implementation of the compact waveguide bi-directional coupler, the internal corners of some parts need to be chamfered. Such rounding must be incorporated into the modeling calculations for the device. The specific design of each implementation mode needs specific calculation according to microwave transmission line theory, mode matching theory and the like. General-purpose three-dimensional commercial software modeling calculations may also be utilized.

According to the bidirectional coupler, the waveguide section is used as the waveguide tube, so that the manufacturing cost is obviously reduced; the two sets of coupling structures are arranged in a flush mode in the axial direction of the waveguide, so that the length of the device is shortened remarkably; the power capacity of the device is greatly improved by arranging the coupling structure to deviate from the center of the wide edge of the waveguide. The device also has flat coupling coefficient frequency response and high directivity coefficient, and can be widely applied to the fields of radar, missile guidance, communication, microwave heating and the like.

Claims

1. A compact waveguide bidirectional coupler is characterized by comprising a rectangular waveguide tube (1) with an axis along the Z direction and a wide edge along the X direction, two coupling holes (2) which are positioned on one or two H surfaces of the waveguide tube (1) along the Y direction and are communicated with the waveguide tube (1), a coupling cavity (3) which is positioned near each coupling hole (2) and is communicated with the coupling hole, a coupling conductor (4) which is positioned in each coupling cavity (3), and two coaxial connectors (5) of which the inner conductors extend into each coupling cavity (3) and are respectively communicated with one end of the coupling conductor (4); the coupling conductor (4) is not connected with the inner wall of the coupling cavity (3); the X, Y and Z directions form a rectangular coordinate system.

2. A compact waveguide bi-directional coupler according to claim 1, wherein both coupling holes (2) are located on the same H-plane of the waveguide tube (1).

A compact waveguide bi-directional coupler according to claim 1, wherein the center lines of the two coupling holes (2) in the Y direction are aligned in the Z direction.

3. A compact waveguide bi-directional coupler according to claim 1, wherein the center lines of the two coupling holes (2) in the Y-direction are offset from the lateral center position of the waveguide (1) in the X-direction by at least 0.05 times the operating wavelength of free space.

4. A compact waveguide bi-directional coupler according to claim 1, wherein said waveguide (1) is machined from standard waveguide profiles.

5. A compact waveguide bi-directional coupler as claimed in claim 1, said overall structure comprising said rectangular waveguide (1), all of said coupling apertures (2), all of said coupling cavities (3), all of said coupling conductors (4), all of said coaxial connectors (5) being mirror symmetric with respect to the YZ plane.

6. A compact waveguide bi-directional coupler as claimed in claim 1, wherein said coupling hole (2) is in the shape of a rectangular parallelepiped, the long side of which is parallel to the axial direction of said waveguide tube (1).

7. A compact waveguide bi-directional coupler as claimed in claim 1, wherein said coupling cavity (3) is shaped as a rectangular parallelepiped with its long side parallel to the axial direction of said waveguide tube (1).

8. A compact waveguide bi-directional coupler as claimed in claim 1, wherein said coupling conductor (4) is in the shape of a rectangular parallelepiped, the long side of which is parallel to the axial direction of said waveguide tube (1).

9. A compact waveguide bi-directional coupler according to claims 7-9, at least one of the coupling structures of which comprises the coupling hole (2), the coupling cavity (3), the coupling conductor (4) and the two coaxial contacts (5) constituting the coupling structure as a whole rotated at least 5 degrees around its symmetry line pointing in the Y-direction.