High performance te21 mode hybrid synthesis network and method of processing the same

Abstract

This invention discloses a high-performance TE21 mode synthesis network and its fabrication method, belonging to the field of single-pulse tracking technology for reflector antennas. It includes a circular waveguide and, from top to bottom, a waveguide network upper layer, a rectangular waveguide middle layer, and a waveguide network lower layer. The rectangular waveguide middle layer mainly consists of eight rectangular waveguides; the lines connecting these eight rectangular waveguides intersect on the central axis of the circular waveguide and are evenly arranged around the axis of the circular waveguide. Both the upper and lower waveguide network layers are 1-to-4 waveguide power dividers; the ends of two 1-to-4 waveguide power dividers are connected to the outer ends of the corresponding rectangular waveguides. The inner ends of the rectangular waveguides extend vertically downwards, cooperating with the circular waveguide as the lower hybrid waveguide port. This invention has low loss, requires no debugging, and can meet the application requirements of antennas in the millimeter-wave band for satellite communication, radar, and radio astronomy.

Description

Technical Field

[0001] This invention discloses a high-performance TE21 mode synthesis network and its fabrication method. It relates to the field of single-pulse tracking technology for reflector antennas, and in particular to the design and fabrication method of a TE21 mode synthesis network, which is applicable to single-pulse tracking reflector antennas in fields such as satellite communication, radar, and telemetry and control. Background Technology

[0002] With the development of modern society and radio communication technology, millimeter wave and terahertz frequencies are increasingly used. Compared with other types of antennas, reflector antennas have the advantages of lower radiation beam sidelobes, narrow main lobe and high gain. Their excellent cost performance makes them the preferred antenna in the field of millimeter wave precision tracking. The monopulse tracking feed system is a key component of the monopulse tracking reflector antenna.

[0003] Monopulse tracking technology involves first transmitting a pulse signal. When this signal reaches the target surface and reflects back, the reflected wave signal is analyzed to obtain the target's position information, such as range, azimuth, and elevation. The target's position deviation information is then input into the antenna servo system for control, thereby achieving tracking. Compared to general precision tracking technologies, monopulse tracking technology offers advantages such as faster tracking speed and higher accuracy, and is widely used in earth stations and mobile communication devices such as those mounted on vehicles and ships.

[0004] The main types of monopulse feeds are: First, multi-horn type, such as four-horn, five-horn, and twelve-horn multi-horn feeds. These exhibit significant sum-difference contradictions, leading to reduced radiation efficiency of the antenna system. Second, multi-horn multi-mode monopulse feeds, such as dual-horn dual-mode and four-horn tri-mode feeds. These have lower sidelobes and axially symmetrical sum-difference beams, slightly reducing the sum-difference contradiction. However, due to the relatively large horn aperture, the obstruction problem is particularly pronounced when using a positive feed, resulting in excessively high sidelobe levels and reduced gain. Third, single-horn multi-mode monopulse feeds. Compared to multi-horn and multi-horn multi-mode feeds, single-horn multi-mode feeds have higher sum beam efficiency, higher difference beam sensitivity, and a larger difference beam slope, effectively resolving the sum-difference contradiction that is difficult to address with reflector antennas.

[0005] The tracking modes used in single-horn multimode single-pulse feeds include TE01, TM01, and TE21 modes. TE01 and TM01 modes can only be used for tracking circularly polarized beacons, while TE21 mode can be used for tracking both circularly polarized and linearly polarized beacons. Therefore, TE21 mode is widely used due to its complete polarization information. The device for TE21 mode tracking is a TE21 mode coupler, which has a circular waveguide as its main waveguide and a rectangular waveguide as its secondary waveguide. A row of coupling holes is opened on the wall of the circular waveguide to achieve energy coupling to the rectangular waveguide. The primary mode is TE11 mode, which is transmitted in the circular waveguide. The TE21 mode entering the circular waveguide is coupled to the secondary waveguide, while the primary mode is suppressed to a certain extent.

[0006] The TE21-mode coupler uses a circular waveguide as the main waveguide, surrounded by eight evenly distributed rectangular waveguides as secondary waveguides. The narrow sides of the rectangular waveguides share a common wall of a certain thickness with the circular waveguides. To achieve differential mode synthesis, traditional differential mode synthesizing networks typically employ bends, HT power dividers, and magic T-shaped waveguides to form a waveguide network. For example, the literature "Research on Single-Pulse Communication Antennas" and "Research and Design of K / Ka Band Single-Pulse Feed Systems" both use waveguide bends and magic T-shaped waveguides to form the differential mode network. This type of synthesizing network has low loss and excellent performance, but the interlacing lateral and longitudinal structures make fabrication difficult. After segmenting and fabricating different waveguides, the connections are complex, the size is large, and it is difficult to guarantee the final performance. In the patent "A Synthesizing Network for a TE21-Mode Coupler," the TE21 mode is extracted through a waveguide coaxial converter, and then a microstrip bridge power divider network is used to achieve differential mode synthesis. The coaxial converter and the power divider network are connected by a coaxial cable. Both the microstrip structure and the coaxial cable lead to excessive loss in the synthesizing network. The patent "A Compact Structure Single-Channel Single-Pulse Feed Source" uses 180° and 90° microstrip bridges in microstrip form to realize a differential-mode synthesis network. Eight equal-phase cables are connected to the input terminals of four 180° bridges, with each of the four 180° bridges connected to the input terminals of two other 180° bridges. The output terminals of the two 180° bridges are connected to the input terminals of the 90° bridges, making consistency difficult to guarantee. To address the issues of excessive losses caused by miniaturization and microstrip circuits, the paper "Design of a Novel C-Band TE21 Mode Circular Polarization Synthesis Network" designs a circular polarization synthesis network in the form of an air stripline. Microstrip synthesis networks have some shortcomings; in millimeter-wave applications, the dielectric substrate is thin and the microstrip lines are thin, making implementation difficult. Based on the principle of 3dB waveguide directional couplers, the paper "Research and Design of Compact Ka-Band TE21 Mode Circular Polarization Synthesis Network" introduces the axial layered design concept of air stripline synthesis networks into the design of waveguide synthesis networks, resulting in a compact waveguide differential mode synthesis network design scheme. However, due to the poor amplitude consistency of the waveguide 3dB bridge in broadband operation, the transmission loss at the synthesis port of this network is large. In summary, there are currently two types of synthesis networks for TE21 mode couplers. One type uses waveguides, which typically uses irregular waveguide bends, HT power dividers, and magic T to form the waveguide network. Although it has low loss and excellent performance, the transverse and longitudinal structures are intertwined, making processing difficult, resulting in large size, complex connections, and the inability to be integrally formed, and requiring a large amount of debugging. The other type uses microstrip, stripline, and 3dB bridges. Due to the high loss of the devices themselves and the poor channel consistency, the overall loss of this type of synthesis network is relatively large, especially in millimeter-wave applications. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the aforementioned background technology and provide a high-performance TE21 mode synthesis network and its fabrication method, thereby realizing a high-performance, compact TE21 mode waveguide synthesis network. According to the design and fabrication method provided by this invention, the complete synthesis network formed by splicing together independently fabricated metal plates has low loss, requires no debugging, and can meet the application requirements of antennas in the millimeter-wave band for satellite communication, radar, and radio astronomy.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A high-performance TE21 mode synthesis network includes a circular waveguide, and further includes an upper waveguide network, a middle rectangular waveguide layer, and a lower waveguide network layer arranged from top to bottom; wherein, the circular waveguide is vertically arranged and runs through the upper waveguide network, the middle rectangular waveguide layer, and the lower waveguide network layer;

[0010] The intermediate layer of the rectangular waveguide is mainly composed of eight rectangular waveguides; the lines connecting the eight rectangular waveguides intersect on the central axis of the circular waveguide and are evenly arranged around the axis of the circular waveguide.

[0011] Both the upper and lower layers of the waveguide network are 1-to-4 waveguide power dividers; the ends of the two 1-to-4 waveguide power dividers are connected to the outer ends of the corresponding rectangular waveguides; the inner ends of the rectangular waveguides extend vertically downwards and cooperate with the circular waveguides to serve as the lower hybrid waveguide ports.

[0012] One of the four-waveguide power splitting networks has its main branch port facing upwards and vertical input; the other has its main branch port facing to one side and horizontal input.

[0013] Furthermore, the rectangular waveguides corresponding to the upper layer of the waveguide network and the rectangular waveguides corresponding to the lower layer of the waveguide network are arranged at intervals.

[0014] Furthermore, the extension direction of the rectangular waveguide is parallel to the central axis of the circular waveguide.

[0015] Furthermore, the upper circular waveguide port flange is a female flange, and the lower hybrid waveguide port flange is a male flange.

[0016] Furthermore, the one-to-four waveguide power divider network is mainly composed of a main branch, a one-to-two branch, and a two-to-four branch; wherein the end of the main branch is connected to two one-to-two branches through a first step structure, and the one-to-two branch is connected to the two-to-four branch through a second step structure.

[0017] Furthermore, the ends of the two-stub four-section segments of the four-waveguide network extend vertically and connect to the outer ends of the corresponding rectangular waveguides in the intermediate layer.

[0018] A method for fabricating a high-performance TE21 model synthesis network, used in the aforementioned high-performance TE21 model synthesis network, is characterized by the following specific steps:

[0019] Step 1: Perform secondary structural design on the TE21 mode synthesized network electrical simulation model according to the processing requirements, and separate it from the middle of the narrow side of the waveguide into four layers of metal plates with groove features.

[0020] Step 2: The metal plates of each layer are processed sequentially by roughing, aging treatment, semi-finishing and finishing.

[0021] Step 3: Position and assemble the metal plate.

[0022] Furthermore, in step 2, a flange is milled out on the corresponding metal plate.

[0023] The beneficial effects of this invention are as follows:

[0024] Compared with the prior art, the advantages of the present invention are that the high-performance TE21 model synthesis network and its processing method adopt planar cavity synthesis technology, which is novel in concept, simple in structure and process, can be processed in layers, and the processing method is simple and feasible, effectively realizing a high-performance TE21 model synthesis network.

[0025] This invention is smaller and lighter than traditional waveguide synthesis networks, and has lower network loss than microstrip and air stripline structures. The fabrication method used here has good fabrication consistency and requires no debugging. It has significant advantages in the millimeter-wave band and is an important improvement over existing technologies. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the present invention;

[0027] Figure 2 This is a schematic diagram of the connection method of the present invention and the TE21 mode coupler connected thereto.

[0028] Figure 3 This is a schematic diagram of the TE21 mode tracker assembled with the TE21 mode coupler of the present invention.

[0029] Figure 4 This is a schematic diagram of the upper surface of the metal plate I of the present invention.

[0030] Figure 5 This is a schematic diagram of the lower surface of the metal plate I of the present invention.

[0031] Figure 6 This is a schematic diagram of the lower surface of the metal plate II of the present invention.

[0032] Figure 7This is a schematic diagram of the upper surface of the metal plate II of the present invention.

[0033] Figure 8 This is a schematic diagram of the lower surface of the metal plate III of the present invention.

[0034] Figure 9 This is a schematic diagram of the upper surface of the metal plate III of the present invention.

[0035] Figure 10 This is a schematic diagram of the lower surface of the metal plate IV of the present invention.

[0036] Figure 11 This is a schematic diagram of the upper surface of the metal plate IV of the present invention.

[0037] Figure 12 This is a schematic diagram showing the connection sequence of metal plate I, metal plate II, metal plate III, and metal plate IV of the present invention.

[0038] Explanation of reference numerals in the attached figures: Metal plate IV—1, Metal plate III—2, Metal plate II—3, Metal plate I—4, Metal plate I circular waveguide port—5, Metal plate I rectangular waveguide port—6, Metal plate I layered HT1—7, Metal plate I layered HT2—8, Metal plate I layered HT3—9, Metal plate I main waveguide connection hole—10, Metal plate I pin hole—11, Metal plate II circular waveguide port—12, Metal plate II rectangular waveguide port—13, Metal plate II layered HT1—14, Metal plate II layered HT2—15, Metal plate II layered HT3—16, Metal plate II layered E Surface bend—17, Metal plate II eight-way layered waveguide—18, Metal plate II pin hole—19, Metal plate III eight-way layered waveguide—20, Metal plate III pin hole—21, Metal plate III layered HT1—22, Metal plate III layered HT2—23, Metal plate III layered HT3—24, Metal plate III waveguide outlet—25, Metal plate IV layered HT1—26, Metal plate IV layered HT2—27, Metal plate IV layered HT3—28, Metal plate IV waveguide outlet—29, Metal plate IV pin hole—30, Metal plate IV main waveguide outlet—31. Detailed Implementation

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings and examples. However, the embodiments described herein are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] A high-performance TE21 mode synthesis network includes a circular waveguide, and further includes an upper waveguide network, a middle rectangular waveguide layer, and a lower waveguide network layer arranged from top to bottom; wherein, the circular waveguide is vertically arranged and runs through the upper waveguide network, the middle rectangular waveguide layer, and the lower waveguide network layer;

[0041] The intermediate layer of the rectangular waveguide is mainly composed of eight rectangular waveguides; the lines connecting the eight rectangular waveguides intersect on the central axis of the circular waveguide and are evenly arranged around the axis of the circular waveguide.

[0042] Both the upper and lower layers of the waveguide network are 1-to-4 waveguide power dividers; the ends of the two 1-to-4 waveguide power dividers are connected to the outer ends of the corresponding rectangular waveguides; the inner ends of the rectangular waveguides extend vertically downwards and cooperate with the circular waveguides to serve as the lower hybrid waveguide ports.

[0043] One of the four-waveguide power splitting networks has its main branch port facing upwards and vertical input; the other has its main branch port facing to one side and horizontal input.

[0044] The rectangular waveguides corresponding to the upper layer of the waveguide network and the rectangular waveguides corresponding to the lower layer of the waveguide network are arranged at intervals.

[0045] The rectangular waveguide extends in a direction parallel to the central axis of the circular waveguide.

[0046] The upper circular waveguide port flange is a female flange, and the lower hybrid waveguide port flange is a male flange.

[0047] The one-to-four waveguide power divider network is mainly composed of a main branch, a one-to-two branch, and a two-to-four branch; the end of the main branch is connected to two one-to-two branches through a first step structure, and the one-to-two branch is connected to the two-to-four branch through a second step structure.

[0048] The ends of the two-stub four-section segments of the four-waveguide network extend vertically and connect to the outer ends of the corresponding rectangular waveguides in the intermediate layer.

[0049] The structure of this embodiment will be further described according to the processing technology:

[0050] Based on a layered waveguide HT power divider, and utilizing a layered fabrication approach, this invention mainly consists of two layers of six waveguide HT power dividers and waveguide cavity wiring for connecting the HT power dividers. In terms of electrical design, each layer of the network considers electrical, structural, and fabrication methods. In terms of fabrication, this invention can be divided into four metal plates and slots on these metal plates, resulting in a simple manufacturing process.

[0051] A high-performance TE21 mode combining network includes metal plates I, II, III, and IV. It employs two stages of three HT power dividers to combine four coupled arms into a linearly polarized differential mode. Another four coupled arms couple a TE21 polarized degenerate mode, which is then combined using the same network to create another path. Two input 3dB waveguide directional couplers are used to achieve dual circular polarization output. Since the waveguide transmission line size is larger than the stripline size at the same frequency, this scheme offers advantages such as simple fabrication, structural stability, and high reliability for the frequency band. The axially layered structure results in very limited lateral space; therefore, the network layers must be compactly arranged to minimize the waveguide device size, while also considering manufacturability, testability, and assemblability. Figure 4 This is a schematic diagram of the synthesized network structure, which uses a stepped design to achieve a reasonable layered structure. Waveguide grooves and HT grooves are machined into each metal plate using CNC precision milling. The four metal plates are positioned and assembled using pins, and then the synthesized network is tightened around the perimeter with screws to obtain a qualified product.

[0052] A high-performance TE21 molded composite network and its fabrication method are disclosed. The TE21 molded composite network comprises four parts: metal plate I, metal plate II, metal plate III, and metal plate IV. Figure 1 As shown, the four metal plates are arranged sequentially from bottom to top. The TE21 mode combining network is electrically composed of six H-plane T-shaped waveguides, multiple H-plane bent waveguides, and E-plane bent waveguides. Specifically, it includes a two-way one-to-four rectangular waveguide power divider network spaced 45° apart axially. Each way includes three H-plane T-shaped waveguides, which respectively complete the low-loss coupling of one TE21 degenerate mode in the circular waveguide.

[0053] The adjacent connecting surfaces of metal plates I, II, III and IV are all the narrow side center tangent of H-plane T-shaped waveguides.

[0054] The TE21 mode synthesis network has a four-port physical structure. Its output ports include an upper circular waveguide port, a lower hybrid waveguide port, and two rectangular waveguide ports on the sidewall. The upper circular waveguide port has a female flange, and the lower hybrid waveguide port has a male flange. One rectangular waveguide port faces upwards, and the other faces horizontally towards the sidewall. The lower hybrid waveguide port includes eight rectangular waveguide ports evenly distributed at 45° axial intervals and one axial circular waveguide port. Its flange is connected to… Figure 2 The TE21 mode coupler shown is connected to the female flange to ensure good electrical contact at both ends of the rectangular waveguide port, and the connection effect is as follows. Figure 3 As shown, the two rectangular waveguide ports are spaced 135° apart around the axial direction of the circular waveguide.

[0055] Depend on Figures 4-11As can be seen, each layer of the TE21 mode combining network contains a half-to-four rectangular waveguide power divider network. The H-plane T-shaped waveguides are all stepped chamfered structures. The first two H-plane T-shaped waveguides are symmetrical about the circular waveguide axis. Figure 4 For example, the first two H-plane T-shaped waveguides are metal plate I-layer HT1 and metal plate I-layer HT2, and the other metal plates are similar. For ease of processing, the bent parts of the symmetrical waveguide transmission lines on the same metal plate are all rounded and chamfered.

[0056] Depend on Figure 12 As shown, the eight-layered waveguides formed by connecting metal plates II and III have four waveguides spaced 90° apart connected to a 1-to-4 splitting network composed of upper metal plates III and IV via bent waveguides. The remaining four waveguides, spaced 90° apart, are connected to a 1-to-4 splitting network composed of lower metal plates II and I. Simultaneously, the upward-opening rectangular waveguide port branch waveguides penetrate metal plates IV, III, and II, and then connect to the splitting network on metal plate I via E-plane bending.

[0057] A method for fabricating a high-performance TE21 model synthesis network mainly includes the following steps:

[0058] Step 1: The electrical simulation model of the TE21 modular synthesized network undergoes secondary structural design based on manufacturing process requirements, comprehensively considering factors such as manufacturability, manufacturing economy, positioning, and connection design. Since waveguide segmented flange connections are not used, it can be further miniaturized and integrated. Furthermore, the use of a symmetrical stepped HT structure facilitates layered processing. The final design is as follows: Figure 12 As shown, it has a four-layer structure, with each layer separated from the middle of the narrow side of the waveguide.

[0059] Step 2: The metal plates separated in Step 1 are all thin-plate structures with features such as grooves. In order to reduce their processing deformation and ensure processing accuracy, a processing strategy of roughing-aging treatment-semi-finishing-finishing is adopted.

[0060] Step 3: Using the same feature as a reference, perform CNC machining of features such as pin holes, waveguide grooves, and HT grooves on each metal plate from Step 1 in a single clamping operation. Simultaneously, to improve positioning accuracy, positioning pins can be replaced with positioning posts. Furthermore, the fit between the pins / posts and the holes can be achieved through a mating method, ensuring a fit accuracy within 5μm. Additionally, the surface roughness of each metal plate should be below Ra1.6, and the flatness should not exceed 0.02mm. A flange for connection to the main waveguide is milled at the upper end of metal plate I, and the main waveguide outlet flange is milled on metal plate IV.

[0061] Step 4: The four metal plates from Step 3 are positioned and assembled using pins, and then the network is tightened around them with screws to obtain a qualified product. Considering structural interference and appearance issues, the screw connection design between each layer adopts "counter-hole / counter-platform + countersunk screw / hex socket head cap screw". When using countersunk screws, attention should be paid to the orientation between the countersunk hole and the countersunk screw head to ensure that the countersunk hole and other important features such as the pin hole are completed in one clamping, avoiding the accuracy loss introduced by different processes, and preventing the orientation effect between the countersunk hole and the countersunk screw head during assembly from affecting the pin hole positioning method.

[0062] In summary, the above are merely preferred application examples of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-performance TE21 mode synthesis network, comprising a circular waveguide, characterized in that, It also includes a waveguide network upper layer, a rectangular waveguide middle layer and a waveguide network lower layer arranged from top to bottom; the waveguide network upper layer, the rectangular waveguide middle layer and the waveguide network lower layer are formed by four layers of metal plates with groove features arranged from top to bottom, wherein the circular waveguide is arranged vertically and runs through the waveguide network upper layer, the rectangular waveguide middle layer and the waveguide network lower layer. The rectangular waveguide intermediate layer includes eight rectangular waveguides; the lines connecting the eight rectangular waveguides intersect on the central axis of the circular waveguide and are evenly arranged around the axis of the circular waveguide. Both the upper and lower layers of the waveguide network are 1-to-4 waveguide power dividers; the ends of the two 1-to-4 waveguide power dividers are connected to the outer ends of the corresponding rectangular waveguides; the inner ends of the rectangular waveguides extend vertically downwards and cooperate with the circular waveguides to serve as the lower hybrid waveguide ports. One of the four-waveguide power splitting networks has its main branch port facing upwards and vertical input; the other has its main branch port facing to one side and horizontal input.

2. The high-performance TE21 model synthesis network according to claim 1, characterized in that, The rectangular waveguides corresponding to the upper layer of the waveguide network and the rectangular waveguides corresponding to the lower layer of the waveguide network are arranged at intervals.

3. The high-performance TE21 model synthesis network according to claim 1, characterized in that, The rectangular waveguide extends in a direction parallel to the central axis of the circular waveguide; two 1-to-4 waveguide power divider networks are arranged at 45° intervals around the central axis of the circular waveguide.

4. The high-performance TE21 model synthesis network according to claim 1, characterized in that, The upper circular waveguide port flange is a female flange, and the lower hybrid waveguide port flange is a male flange.

5. The high-performance TE21 model synthesis network according to claim 1, characterized in that, The 1-to-4 waveguide power divider network includes a main branch, a 1-to-2 branch, and a 2-to-4 branch; wherein the end of the main branch is connected to two 1-to-2 branches through a first step structure, and the 1-to-2 branch is connected to the 2-to-4 branch through a second step structure.

6. The high-performance TE21 model synthesis network according to claim 5, characterized in that, The ends of the two-to-four branches of the one-to-four waveguide network extend vertically and connect to the outer ends of the corresponding rectangular waveguides in the middle layer.

7. A method for fabricating a high-performance TE21 model synthesis network, used to fabricate a high-performance TE21 model synthesis network as described in any one of claims 1 to 6, characterized in that, The specific steps are as follows: Step 1: Perform secondary structural design on the TE21 mode synthesized network electrical simulation model according to the processing requirements. Separate the TE21 mode synthesized network electrical simulation model from the middle of the narrow side of the waveguide into four layers of metal plates with groove features. Step 2: The metal plates of each layer are processed sequentially by roughing, aging treatment, semi-finishing and finishing. Step 3: Position and assemble the metal plate.

8. The fabrication method of a high-performance TE21 model synthesis network according to claim 7, characterized in that, In step 2, the flange is milled out on the corresponding metal plate.

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