Ku compact high-isolation orthogonal mode coupler

Abstract

The utility model discloses a Ku compact high-isolation orthogonal mode coupler. The Ku compact high-isolation orthogonal mode coupler comprises a cross matching junction, a pair of short 180-degree waveguide bends, a pair of long 180-degree waveguide bends, two Y-shaped power combiners and two 90-degree waveguide bends. Two opposite rectangular waveguide ports of a cross matching junction are respectively connected with a section of long waveguide I and a section of short waveguide I and then are respectively connected with a 180-degree waveguide bend, and the tail ends of the pair of 180-degree waveguide bends are respectively converged and connected with a Y-type power combiner through a section of long waveguide II and a section of short waveguide II. And the Y-shaped power combiner is connected with a 90-degree waveguide bend. The matching table structure is composed of a rectangular table and an arc-shaped quadrangular frustum pyramid structure, the matching performance and the isolation degree are greatly improved, meanwhile, the structure is machined in a lower screw tapping mode, the difficulty caused by direct machining is avoided, and the precision is well improved.

Description

Technical Field

[0001] This invention relates to the field of microwave technology, and in particular to a compact, high-isolation orthogonal mode coupler for the Ku band, which is widely used in satellite communications, radar systems and other high-frequency communication systems. Background Technology

[0002] In modern communications, with the increasing demand for high-frequency bandwidth, the Ku-band, due to its excellent frequency characteristics and small antenna size, is widely used in satellite communications, radar detection, and military applications. To achieve high-efficiency transmission, orthogonal mode couplers (EMCs) have become a key component in the system. Existing EMCs suffer from problems such as large size and low isolation, failing to meet the requirements of high isolation, compact size, and high performance, as exemplified by the coaxial waveguide EMC disclosed in Chinese Patent Publication No. CN207517840U. Therefore, there is an urgent need for a new type of compact, high-isolation EMC to meet the requirements of modern communication systems for high efficiency, low power consumption, and high performance.

[0003] Orthogonal mode couplers (EMCs) can separate electromagnetic waves into two orthogonal polarization modes. Symmetrical EMCs can suppress the excitation of some higher-order modes and are therefore widely used. Common symmetrical EMCs include the Boifot and Turnstile types. The Boifot type consists of a Boifot matching junction, a Y-type power combiner, and a bent E-plane waveguide. Due to the lack of central symmetry in its matching structure, its polarization isolation cannot be well controlled. Correspondingly, the Turnstile type consists of a rotary gate and two corresponding Y-type power combiners. Its structure has central symmetry and better polarization isolation. However, to maintain this structural property, the different longitudinal heights of the polarization waveguides lead to an increase in the size of the EMC, resulting in a complex structure that is not conducive to achieving a compact design. Improving the isolation of the structure without increasing its size is the main challenge in the design of this EMC. The matching stage of the cross-shaped rotary gate structure has a significant impact on the standing wave ratio and isolation performance of the structure. Previous researchers have adjusted the performance by improving the matching stage structure. However, in actual manufacturing, the internal machining accuracy of the orthogonal mode coupler also seriously affects the overall performance of the structure. Therefore, designing a Ku-type compact, high-isolation orthogonal mode coupler to meet the needs of microwave communication is of great practical significance. Summary of the Invention

[0004] This utility model patent provides a Ku-type compact, high-isolation orthogonal mode coupler to solve the problems mentioned in the background art.

[0005] The technical solution adopted in this utility model is as follows:

[0006] A Ku-type compact high-isolation orthogonal mode coupler includes a cross-matching junction, a pair of short 180° waveguide bends, a pair of long 180° waveguide bends, two Y-type power combiners, and two 90° waveguide bends.

[0007] Furthermore, the cross-shaped matching junction is composed of a circular waveguide and a cross-shaped rectangular waveguide. A matching platform structure is provided at the center where the cross-shaped rectangular waveguide and the circular waveguide coincide, and the axis of symmetry of the matching platform structure coincides with the central axis of the circular waveguide. The matching platform structure is composed of a rectangular platform and an arc-shaped quadrangular platform structure, and is a centrally symmetrical structure. The side length of the rectangular platform is 0.325λ~0.335λ, and the height is 0.08λ~0.085λ, where λ is the wavelength corresponding to the center frequency. The top side length of the arc-shaped quadrangular platform is equal to the side length of the rectangular platform, the bottom side length is 0.525λ~0.535λ, and the height is 0.089λ~0.1λ. In order to adjust the matching, the upper and lower bottom surfaces of the quadrangular platform are transitioned by circular arcs with a radius of 1mm.

[0008] Furthermore, for polarization 1, the two opposite rectangular waveguide ports of the cross-matching junction are respectively connected to a long waveguide 1 and a short waveguide 1, and then each is connected to a short 180° waveguide bend. The ends of the pair of short 180° waveguide bends are then connected to a Y-type power combiner via a long waveguide 2 and a short waveguide 2, respectively. Each Y-type power combiner is connected to a 90° waveguide bend. For polarization 2, the above structure is formed by rotating 90° around the central axis of the circular waveguide. In order to prevent the waveguide structures from overlapping, the cross-matching junction is connected to a pair of long 180° waveguide bends. The diameter of the short 180° waveguide bend is 1.2λ to 1.25λ, and the diameter of the long 180° waveguide bend is 1.35λ to 1.4λ.

[0009] Furthermore, the Y-type power combiner includes a matching step one, a matching step two, a matching step three, a matching step four, and a pair of 90° circular bends. The width of the matching step one is 0.43λ to 0.45λ and the height is 0.055λ to 0.06λ. The width of the matching step two is 0.56λ to 0.57λ and the height is 0.12λ to 0.13λ. The width of the matching step three is 0.7λ to 0.71λ and the height is 0.13λ to 0.14λ. The width of the matching step four is 0.79λ to 0.8λ and the height is 0.1λ to 0.11λ. The radius of the 90° circular bends is 0.46λ to 0.47λ. The signal input gradually transitions to the Y-type power combiner from the 90° waveguide bends.

[0010] Furthermore, in order to reduce the phase deviation of signal synthesis, the length of the structure, which consists of a long waveguide, a short waveguide, and a cross-shaped matching junction, is equal to the length of the long waveguide, a short waveguide, and the end of the Y-type power combiner, with a total length of 75.9 mm.

[0011] Furthermore, the feed rectangular waveguides are all standard waveguides BJ-140, and the circular waveguides have a diameter of 18.2 mm.

[0012] Furthermore, the structure described above is an internal cavity structure. In actual fabrication, its exterior is made of metal. Except for the matching stage structure, the other structures are all structures with waveguide pathways opened inside the metal shell. The matching stage structure is fabricated by using bottom-tapping screws. The screws at the bottom of the cross-shaped matching junction are fixed to the entire structure, avoiding the difficulties caused by directly fabricating the matching stage structure and greatly improving the accuracy.

[0013] The advantages of this application compared to the prior art are as follows:

[0014] 1. The design of the matching stage structure affects the matching performance of the orthogonal mode coupler and can improve the isolation of the two polarizations. This design adopts a rectangular stage and an arc-shaped quadrangular truncated stage structure for the matching stage. By adjustment, the dual polarization standing wave ratio is better than 1.3 and the isolation is better than -70dB.

[0015] 2. The mating table structure is machined using a tapping method, which avoids the difficulties caused by direct machining of the mating table and facilitates actual adjustment, thus greatly improving accuracy.

[0016] 3. It features low VSWR, high isolation, compact structure, and excellent electrical performance within its operating bandwidth. Furthermore, it can achieve good equal-phase transmission between the common port circular waveguide and the two orthogonal rectangular waveguide ports, thus achieving good dual-polarization performance. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a Ku-type compact high-isolation orthogonal mode coupler according to the present invention;

[0018] Figure 2 This is a schematic diagram of the cross-shaped matching knot structure of this utility model;

[0019] Figure 3 This is a schematic diagram of the Y-type power combiner structure of this utility model;

[0020] Figure 4 This is the standing wave test diagram of this utility model;

[0021] Figure 5 This is a test diagram of the port isolation of this utility model;

[0022] Figure 6 This is a test diagram of the transmission coefficient of this utility model.

[0023] In the diagram: 1. Cross-shaped matching junction; 1-1. Circular waveguide; 1-2. Cross-shaped rectangular waveguide; 1-3. Matching platform structure; 1-4. Long waveguide one; 1-5. Short waveguide one; 2. Short 180° waveguide bend; 2-1. Long waveguide two; 2-2. Short waveguide two; 3. Long 180° waveguide bend; 4. Y-type power combiner; 4-1. Matching step one; 4-2. Matching step two; 4-3. Matching step three; 4-4. Matching step four; 4-5. 90° circular bend; 5. 90° waveguide bend; Detailed Implementation

[0024] Now combined Figures 1 to 6 This utility model will be described in detail below. For example... Figure 1 As shown, a Ku-type compact high-isolation orthogonal mode coupler includes a cross-matching junction 1, a pair of short 180° waveguide bends 2, a pair of long 180° waveguide bends 3, two Y-type power combiners 4, and two 90° waveguide bends 5.

[0025] like Figure 2 As shown, the cross-shaped matching junction 1 consists of a circular waveguide 1-1 and a cross-shaped rectangular waveguide 1-2, which can connect the TE in the circular waveguide port. 11 The mode is converted to a clean, orthogonal TE output at the rectangular waveguide port. 10 To achieve good dual polarization, a matching stage structure 1-3 is located at the center of the cross-shaped rectangular waveguide 1-2 and the circular waveguide 1-1. Changing the matching stage structure 1-3 can adjust the matching performance of the orthogonal mode coupler. Optimization of different matching stage structures revealed a significant impact on the structural matching. Therefore, this design adopts a rectangular stage and an arc-shaped quadrangular truncated pyramid structure, which is a centrally symmetrical structure that can effectively achieve mode synthesis and separation. The axis of symmetry of the matching stage structure 1-3 coincides with the central axis of the circular waveguide 1-1. The rectangular stage has a side length of 6.65 mm and a height of 1.65 mm. The top side length of the arc-shaped quadrangular truncated pyramid is equal to the side length of the rectangular stage, the bottom side length is 10.45 mm, and the height is 1.9 mm. To adjust the matching, the upper and lower base surfaces of the quadrangular truncated pyramid are transitioned by circular arcs with a radius of 1 mm.

[0026] like Figure 1As shown, the orthogonal mode coupler has two polarizations. For polarization 1, the two opposite rectangular waveguide ports of the cross-matching junction 1 are connected to a long waveguide 1-4 and a short waveguide 1-5, respectively, and then each is connected to a short 180° waveguide bend 2. The ends of the pair of short 180° waveguide bends 2 are then connected to a Y-type power combiner 4 through a long waveguide 2-1 and a short waveguide 2-2, respectively. Each Y-type power combiner 4 is connected to a 90° waveguide bend 5. For polarization 2, the structure of polarization 1 is formed by rotating 90° around the central axis of the circular waveguide 1-1. In order to prevent the waveguide structures from overlapping, the cross-matching junction 1 is connected to a pair of long 180° waveguide bends 3. In order to avoid mutual interference between the two waveguide paths and to improve the compactness of the structure, the diameter of the short 180° waveguide bend 2 is finally determined to be 24 mm, and the diameter of the long 180° waveguide bend 3 is 37.9 mm.

[0027] like Figure 3 As shown, the Y-type power combiner 4 can convert the TE in the rectangular waveguide 10 The mode is split into two parallel transmission paths, including matching step 1 (4-1), matching step 2 (4-2), matching step 3 (4-3), matching step 4 (4-4), and a pair of 90° circular bends (4-5). Good matching performance can be achieved by adjusting the matching steps. Matching step 1 (4-1) has a width of 8.8 mm and a height of 1.6 mm, matching step 2 (4-2) has a width of 11.3 mm and a height of 2.5 mm, matching step 3 (4-3) has a width of 14.1 mm and a height of 2.6 mm, matching step 4 (4-4) has a width of 15.8 mm and a height of 2.1 mm, and the radius of the 90° circular bends (4-5) is 9.4 mm. The signal input gradually transitions from the 90° waveguide bends (5) to the Y-type power combiner (4), while greatly reducing the longitudinal dimension of the orthogonal mode coupler.

[0028] like Figure 1 As shown, in order to reduce the phase deviation of signal synthesis, the length of long waveguide 1-4 plus short waveguide 1-5 plus cross matching junction 1 is equal to the length of long waveguide 2-1 plus short waveguide 2-2 plus the end of Y-type power combiner 4, which ensures the integrity of the structure. The matching can be improved by adjusting the waveguide length, and the total length is finally determined to be 75.9mm.

[0029] like Figure 1 As shown, the structure described above is an internal cavity structure. In actual fabrication, its exterior is made of metal. Except for the matching stage structure, the other structures are all structures with waveguide paths running through the metal shell. The matching stage structure is fabricated by using a bottom-tapping screw method. The screws at the bottom of the cross-shaped matching junction are fixed to the entire structure, avoiding the difficulties caused by directly fabricating the matching stage structure and greatly improving the accuracy.

[0030] like Figure 4-6As shown, the feed rectangular waveguides are all standard waveguides BJ-140, and the circular waveguides have a diameter of 18.2mm. The orthogonal mode coupler structure was optimized and simulated to obtain the port standing wave ratio, isolation and transmission coefficient test diagrams. In the 12-18GHz frequency band, the standing wave ratio is better than 1.3, the isolation is better than 70dB, and the transmission coefficient is stable at around 0dB. All indicators are excellent and meet the engineering requirements.

[0031] The above description is only an embodiment of this utility model. For those skilled in the art, several improvements and modifications can be made without departing from the principle of this utility model, and these improvements and modifications should also be considered within the protection scope of this utility model.

Claims

1. A Ku-type compact high-isolation orthogonal mode coupler, characterized in that: It includes a cross-shaped matching junction (1), a pair of short 180° waveguide bends (2), a pair of long 180° waveguide bends (3), two Y-type power combiners (4), and two 90° waveguide bends (5). The left and right ends of the cross-shaped matching junction (1) are connected to the short 180° waveguide bends (2), and the front and rear ends of the cross-shaped matching junction (1) are connected to the long 180° waveguide bends (3). The bottom of both the short 180° waveguide bends (2) and the long 180° waveguide bends (3) are connected to the Y-type power combiners (4), and the bottom of the Y-type power combiners (4) is connected to the 90° waveguide bends (5).

2. The Ku-type compact high-isolation orthogonal mode coupler according to claim 1, characterized in that: The cross-shaped matching junction (1) consists of a circular waveguide (1-1) and a cross-shaped rectangular waveguide (1-2). A matching platform structure (1-3) is provided at the center where the cross-shaped rectangular waveguide (1-2) and the circular waveguide (1-1) coincide. The axis of symmetry of the matching platform structure (1-3) coincides with the central axis of the circular waveguide (1-1). The matching platform structure (1-3) is composed of a rectangular frustum and an arc-shaped quadrangular frustum. The matching platform structure (1-3) is a centrally symmetric structure, and the side length of the rectangular frustum is 0.

325. λ ~0.335 λ The height is 0.08 λ ~0.085 λ , λ Given the wavelength corresponding to the center frequency, the top side length of the curved truncated pyramid is equal to the side length of the rectangular truncated pyramid, and the bottom side length is 0.

525. λ ~0.535 λ The height is 0.089 λ ~0.1 λ The upper and lower bases of the truncated pyramid are transitioned by circular arcs with a radius of 1mm.

3. The Ku-type compact high-isolation orthogonal mode coupler according to claim 1, characterized in that: The orthogonal mode coupler includes polarization I and polarization II. For polarization I, the two opposite rectangular waveguide ports of the cross-matching junction (1) are respectively connected to a long waveguide I (1-4) and a short waveguide I (1-5), and then each is connected to a short 180° waveguide bend (2). The ends of the pair of short 180° waveguide bends (2) are then connected to a Y-type power combiner (4) through a long waveguide II (2-1) and a short waveguide II (2-2), respectively. Each Y-type power combiner (4) is connected to a 90° waveguide bend (5). Polarization II is formed by rotating polarization I by 90° around the central axis of the circular waveguide (1-1). The cross-matching junction (1) is connected to a pair of long 180° waveguide bends (3), and the diameter of the short 180° waveguide bends (2) is 1.2 mm. λ ~1.25 λ The waveguide bend is 180° long (3) with a diameter of 1.

35. λ ~1.4 λ .

4. The Ku-type compact high-isolation orthogonal mode coupler according to claim 1, characterized in that: The Y-type power combiner (4) includes matching step one (4-1), matching step two (4-2), matching step three (4-3), matching step four (4-4), and a pair of 90° circular bends (4-5). The width of matching step one (4-1) is 0.

43. λ ~0.45 λ The height is 0.

055. λ ~0.06 λ The width of step 2 (4-2) is 0.

56. λ ~0.57 λ The height is 0.

12. λ ~0.13 λ The width of step three (4-3) is 0.

7. λ ~0.71 λ The height is 0.

13. λ ~0.14 λ The width of step four (4-4) is 0.

79. λ ~0.8 λ The height is 0.

1. λ ~0.11 λ The radius of the 90° circular bend (4-5) is 0.46λ~0.47λ, and the signal input gradually transitions from the 90° waveguide bend (5) to the Y-type power combiner (4).

5. A Ku-type compact high-isolation orthogonal mode coupler according to claim 3, characterized in that: The length of the long waveguide 1 (1-4) plus the short waveguide 1 (1-5) plus the cross-matching junction (1) is equal to the length of the long waveguide 2 (2-1) plus the short waveguide 2 (2-2) plus the end of the Y-type power combiner (4), with a total length of 75.9 mm.

6. A Ku-type compact high-isolation orthogonal mode coupler according to claim 1, characterized in that: The feed rectangular waveguides of the orthogonal mode couplers are all standard waveguides BJ-140, and the circular waveguides have a diameter of 18.2 mm.

7. A Ku-type compact high-isolation orthogonal mode coupler according to claim 1, characterized in that: The orthogonal mode coupler has an internal cavity structure and the outside of the orthogonal mode coupler is metal. The matching platform structure (1-3) is processed by tapping screws at the bottom. The cross matching junction (1) is fixed to the entire structure by screws at the bottom.

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