A high-performance compact terahertz circular polarizer based on diagonal ridge integration

Abstract

This invention discloses a high-performance, compact terahertz circular polarizer based on integrated diagonal ridges, belonging to the field of terahertz passive device technology. It solves the technical problems of insufficient broadband performance of current terahertz circular polarizers, the need for an additional 45° transition structure in existing devices, low system integration, and the tendency to introduce discontinuities. The invention includes: a metal shell containing a cavity extending through both ends of the shell; a square waveguide formed by the cavity, with square ridges on two opposite edges along the length of the waveguide; a first corner corrugated segment disposed on the square ridges; and a second corner corrugated segment disposed on the other two edges along the length of the waveguide, with the first and second corner corrugated segments offset from each other along the length of the waveguide. This invention has advantages such as integrated structure and compact design.

Description

Technical Field

[0001] This invention belongs to the field of terahertz passive device technology, specifically relating to a high-performance compact terahertz circular polarizer based on diagonal ridge integration. Background Technology

[0002] Terahertz waves (0.1 THz~10 THz) lie between infrared and microwave frequencies. While frequency resources are abundant and not yet widely used, their advantages, such as high speed, wide bandwidth, and strong anti-interference capabilities, make them a key technology for future high-speed communication. With the development of wireless communication technology, antennas have become a key research focus in the field of terahertz technology and are also crucial components in wireless communication systems. However, in applications such as satellite communication, radio astronomy, and radar detection, linearly polarized antennas are no longer sufficient, highlighting the increasing importance of circularly polarized antennas. Circular polarizers are key components in the feed system of circularly polarized antennas. Currently, there are various types of circular polarizers, including waveguide type, dielectric insert type, and reflector type. Among them, waveguide circular polarizers, by introducing special structures into the waveguide to change the waveguide's dispersion characteristics, achieve phase shifting. They offer advantages such as low insertion loss and high power capacity, making them suitable for applications in terahertz antenna systems.

[0003] Because of the short wavelength in the terahertz band, device performance is highly sensitive to factors such as burrs generated during manufacturing and assembly errors. This places high demands on the design and fabrication of circular polarizers, making it extremely important to simplify their structure and fabrication methods. On the other hand, in power supply systems, to improve system compatibility, circular polarizers are typically required to have excellent broadband performance. While single-structure circular polarizers are relatively simple, achieving excellent broadband performance is extremely challenging.

[0004] In dual-circularly polarized antenna feeding systems, circular polarizers are typically used in conjunction with orthogonal mode couplers. The linearly polarized wave emitted from the output port of the orthogonal mode coupler passes through a transition structure, where the electric field and the waveguide boundary rotate 45° relative to each other. At the input port of the circular polarizer, this can be decomposed into two orthogonal linearly polarized waves, thus achieving a phase shift effect on these two waves. Currently, stepped waveguide 45° transition structures are commonly used. However, these transition structures often require separate design and fabrication, increasing the time and economic cost of the components. Moreover, due to the requirement for low insertion loss in the feed system, this structure usually requires a transition of 4th order or higher, making it difficult to reduce its physical length. This not only reduces the system's integration density but also introduces gaps at the junctions with upstream and downstream components during assembly, resulting in discontinuities and resonance. Summary of the Invention

[0005] This invention discloses a high-performance compact terahertz circular polarizer based on diagonal ridge integration, which aims to solve the technical problems of insufficient broadband performance of current terahertz circular polarizers, the need for an additional 45° transition structure in existing devices, low system integration, and easy introduction of discontinuities.

[0006] To solve the aforementioned technical problems, the present invention adopts the following technical solution:

[0007] A high-performance, compact terahertz circular polarizer based on integrated diagonal ridge patterns includes:

[0008] A metal shell, wherein a cavity is provided inside the metal shell, and both ends of the cavity penetrate the metal shell;

[0009] A square waveguide, wherein the cavity forms the square waveguide, and square ridges are provided on two opposite ridges along the length direction of the square waveguide;

[0010] The first corner corrugated section is disposed on the square ridge;

[0011] The second corner corrugated segment is disposed on two other ridges along the length direction of the square waveguide, and the first corner corrugated segment and the second corner corrugated segment are offset from each other along the length direction of the square waveguide.

[0012] In this invention, the metal shell provides external support and electromagnetic shielding for the entire circular polarizer, while the internal cavity forms a structure such as a square waveguide. The two ends of the square waveguide extend through both ends of the cavity, serving as the input and output ports, respectively. The square waveguide, acting as the main transmission line, has a square cross-section, with its two ends serving as the input and output ports, respectively. The TE signal is fed in through the input port. 10 A coordinate system is established with the electric field amplitude direction of the electromagnetic wave as the x-axis, the magnetic field amplitude direction as the y-axis, the electromagnetic wave propagation direction as the z-axis, and one vertex of the input port of the square waveguide as the origin. A square ridge is set on the square waveguide along the z-axis, and one edge of the square ridge coincides with a set of diagonal edges of the square waveguide. The input port, the integrated ridge structure, the second corner corrugated segment, and the output port are cascaded through the square waveguide in sequence to form an electromagnetic signal path. The integrated ridge structure is formed by the spatial overlap of the square ridge and the first corner corrugated segment. The integrated ridge structure and the second corner corrugated segment produce opposite phase frequency characteristics and compensate for each other, thereby obtaining an optimal phase difference of close to 90° in a very wide frequency band.

[0013] Preferably, the first corner corrugated segment includes a plurality of first corner corrugations, and the plurality of first corner corrugations are evenly arranged along the length direction of the square ridge.

[0014] The second corner corrugated segment includes a plurality of second corner corrugations, which are evenly arranged along the length direction of the square waveguide. Both the first corner corrugation and the second corner corrugation are connected to the square waveguide.

[0015] Preferably, both the first and second corner corrugations are L-shaped.

[0016] After adopting this technical solution, it should be noted that the L-shaped corrugation refers to the groove that extends from the diagonal edge of the square waveguide to the two adjacent walls, forming a right-angle bend.

[0017] Preferably, the two ends of the first corner corrugation extend to half the position of the surface corresponding to the square waveguide, and the two ends of the second corner corrugation also extend to half the position of the surface corresponding to the square waveguide.

[0018] After adopting this technical solution, it should be noted that the square ridge provides most of the phase difference and intrinsic phase frequency characteristics. Its xy cross-sectional dimensions need to be related to the z-axis length of the square ridge, so as to form a periodic structure with the first corner corrugation. The length of this periodic structure in the z-axis direction constitutes the effective phase shift length of this part. The corrugations within the period provide the characteristic phase frequency characteristics of this application. The corrugation width of the second corner corrugation along the z-axis constitutes the effective phase shift length of this application. The corrugations within the period provide the compensated phase frequency characteristics of this application. The milling depth of the first corner corrugation provides the characteristic propagation constant of this application. Its extension length on the two adjacent boundaries of the square waveguide is half the side length of the square waveguide to facilitate cutting and processing. The milling depth of the second corner corrugation provides the compensated propagation constant of this application. Its extension length on the two adjacent boundaries of the square waveguide is also half the side length of the square waveguide.

[0019] It should also be noted that the square waveguide, the first corner corrugation, the second corner corrugation, and the square ridge are integrally formed by milling.

[0020] Preferably, the metal shell includes a first metal shell and a second outer shell, wherein the first metal shell and the second outer shell are respectively provided with a first cavity and a second cavity, and the cavity is composed of the first cavity and the second cavity.

[0021] After adopting this technical solution, it should be noted that the metal shell is divided into two parts along the central symmetry plane of the square waveguide, namely the xz plane, namely the first metal shell and the second outer shell, which can be precision milled respectively. The first cavity and the second cavity completely surround the electromagnetic path, realizing the constraint of the degree of freedom.

[0022] Preferably, the first metal shell and the second outer shell are further provided with pin hole assemblies, and the first metal shell and the second outer shell are respectively provided with clamping holes for bolts to pass through.

[0023] After adopting this technical solution, it should be noted that the pin hole assembly is used for precise positioning during mold closing, ensuring accurate alignment of the cavity edges of the upper and lower shells to avoid gaps. Bolts are inserted into the clamping holes and tightened to apply uniform clamping force, ensuring a tight fit between the upper and lower shells and preventing gaps between the cavities that could introduce discontinuities at the boundaries.

[0024] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0025] 1. The present invention provides a high-performance compact terahertz circular polarizer based on diagonal ridge integration. It utilizes two waveguide structures with opposite phase frequency characteristics, square ridge and corner corrugation. The first corner corrugation segment is set on the square ridge and the second corner corrugation segment is set on another set of diagonal edges of the square waveguide. The frequency dependence of the structure cancels each other out, realizing the excellent full-band characteristics of the circular polarizer. At the same time, it has high quadrature mode amplitude consistency, low insertion loss and simple structure.

[0026] 2. The present invention provides a high-performance compact terahertz circular polarizer based on diagonal ridge integration, in which the first and second ridge segments are both set on the diagonal of the square waveguide. When forming a system with devices such as orthogonal mode couplers, it can be directly cascaded, eliminating the 45° transition structure and thus reducing the physical length of the system.

[0027] 3. The present invention provides a high-performance compact terahertz circular polarizer based on diagonal ridge integration, which spatially overlaps the first set of diagonal corrugations with square ridges, further improving the overall integration of the antenna feed system. Attached Figure Description

[0028] The present invention will be described by way of example and with reference to the accompanying drawings, wherein:

[0029] Figure 1 This is a structural diagram of the electromagnetic signal path of the present invention;

[0030] Figure 2 This is a schematic diagram of the metal shell structure of the present invention;

[0031] Figure 3 This invention relates to the phase difference and amplitude difference of two polarized waves orthogonal along the diagonal of the output port;

[0032] Figure 4 This invention relates to the insertion loss and return loss of the polarized wave fed diagonally along the input port.

[0033] Figure label:

[0034] 1-Square waveguide, 2-Square ridge, 3-First corner corrugation, 4-Second corner corrugation, 5-First metal shell, 6-Pin hole assembly, 7-Pressure hole, 8-First cavity. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. The components of the embodiments of this application described and marked in the accompanying drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0036] In the description of the embodiments of this application, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0037] The following is combined Figures 1-4 The present invention will be described in detail below.

[0038] A high-performance, compact terahertz circular polarizer based on integrated diagonal ridge patterns, such as Figure 1 , Figure 2 As shown, it includes:

[0039] A metal shell, wherein a cavity is provided inside the metal shell, and both ends of the cavity penetrate the metal shell;

[0040] Square waveguide 1, the cavity forms the square waveguide 1, and square ridges 2 are provided on two opposite ridges along the length direction of the square waveguide 1.

[0041] The first corner corrugated section is disposed on the square ridge 2;

[0042] The second corner corrugated segment is disposed on two other ribs along the length direction of the square waveguide 1, and the first corner corrugated segment and the second corner corrugated segment are offset from each other along the length direction of the square waveguide 1.

[0043] In this embodiment, the metal shell provides external support and electromagnetic shielding for the entire circular polarizer. The internal cavity forms a structure such as a square waveguide 1, with both ends of the square waveguide 1 penetrating both ends of the cavity, serving as the input port and output port respectively. The square waveguide 1 acts as the main transmission line, with a square cross-section, and its two ends serve as the input port and output port respectively. Figure 2 As shown, a coordinate system is established with the electric field amplitude direction of the TE10 mode electromagnetic wave fed into the input port as the x-axis, the magnetic field amplitude direction as the y-axis, the electromagnetic wave propagation direction as the z-axis, and one vertex of the input port of the square waveguide 1 as the origin. A square ridge 2 is set on the square waveguide 1 along the z-axis. One edge of the square ridge 2 coincides with a set of diagonal edges of the square waveguide 1. In addition, both square ridges 2 are provided with a first corner corrugated segment. The input port, the square ridge 2 part, the second corner corrugated segment 4 and the output port are cascaded through the square waveguide 1 in sequence to form an electromagnetic signal path. The square ridge 2 part is formed by the spatial overlap of the square ridge 2 and the first corner corrugated segment, thus forming an integrated ridge and corrugated structure. The integrated ridge and corrugated structure and the second corner corrugated segment produce opposite phase frequency characteristics and compensate for each other, thereby obtaining an optimal phase difference of close to 90° in a very wide frequency band.

[0044] Furthermore, it should be emphasized that Figure 1 The structure of the electromagnetic signal path of this invention is shown, wherein the square waveguide 1 is not an independent solid part, but a square hollow path directly formed by the cavity inside the metal shell. In other words, the wall of the square waveguide 1 is the inner wall of the metal shell, and the two are an integral structure. Figure 1 To showcase the internal features, all structures in the actual product are formed by milling on the same metal block;

[0045] Furthermore, in this embodiment, the ridge-integrated portion and the second corner corrugated segment are directly coupled through a square waveguide 1, the length of which is 0.183 mm. The unit structure lengths of the ridge-integrated portion and the second corner corrugated segment on the z-axis are 0.5 mm and 0.4 mm, respectively. The length of the unit structure of the ridge-integrated portion refers to the sum of the length of a first corner corrugation 3 and the spacing between its adjacent first corner corrugations 3. Similarly, the length of the unit structure of the second corner corrugated segment refers to the sum of the length of a second corner corrugation 4 and the spacing between its adjacent second corner corrugations, so as to achieve impedance matching within the periodic structure.

[0046] In this embodiment, the dimensions of the metal shell are 21.4mm×24mm×24mm, and the side length of the waveguide aperture of the square waveguide 1 is 1.092mm.

[0047] In this embodiment, the first corner corrugated segment includes a plurality of first corner corrugations 3, and the plurality of first corner corrugations 3 are evenly arranged along the length direction of the square ridge 2.

[0048] The second corner corrugated segment includes a plurality of second corner corrugations 4, which are uniformly arranged along the length of the square waveguide 1. The first corner corrugation 3 and the second corner corrugations 4 are both connected to the square waveguide 1. The square ridge 2 provides most of the phase difference and the intrinsic phase frequency characteristics. Its xy cross-sectional dimensions need to be related to the length of the square ridge 2 on the z-axis. Therefore, in this embodiment, it is taken as 0.149 mm × 0.149 mm, thus forming a periodic structure with the first corner corrugation 3. The length of this periodic structure in the z-axis direction constitutes the effective phase shift length of the corresponding part. The total period length is 15.6 mm. The corrugations within the period provide characteristic phase frequency characteristics. The width of this corrugation in the z-axis direction is 0.25 mm, and the number of periods is 39. The corrugation width of the second corner corrugation 4 along the z-axis constitutes the effective phase shift length of the corresponding part. The total period length is 1.65 mm. The corrugations within the period provide compensated phase frequency characteristics. The width of this corrugation in the z-axis direction is 0.154 mm, and the number of periods is 4.

[0049] In this embodiment, both the first corner corrugation 3 and the second corner corrugation 4 are L-shaped. An L-shaped corrugation refers to a groove that extends from the diagonal edge of the square waveguide 1 to two adjacent walls, forming a right-angle bend.

[0050] In this embodiment, the two ends of the first corner corrugation 3 extend to half the position corresponding to the surface of the square waveguide 1, and the two ends of the second corner corrugation 4 also extend to half the position corresponding to the surface of the square waveguide 1. The milling depth of the first corner corrugation 3 is 0.1 mm to provide the characteristic propagation constant in this embodiment, and its extension length on the two adjacent boundaries of the square waveguide 1 is half the side length of the square waveguide 1, i.e., 0.546 mm, to facilitate cutting and processing; the milling depth of the second corner corrugation 4 is 0.253 mm to provide the compensation propagation constant in this embodiment, and its extension length on the two adjacent boundaries of the square waveguide 1 is also half the side length of the square waveguide 1, i.e., 0.546 mm.

[0051] In another embodiment, such as Figure 2 As shown, the metal shell includes a first metal shell 5 and a second outer shell. The first metal shell 5 and the second outer shell each have a first cavity 8 and a second cavity, respectively. Each cavity is composed of the first cavity 8 and the second cavity. The metal shell is divided into upper and lower parts along the central symmetry plane of the square waveguide 1, i.e., the xz plane, forming the first metal shell 5 and the second outer shell. These parts can be precision milled separately. During assembly, the first cavity 8 and the second cavity work together to completely surround the angular corrugations, achieving degree-of-freedom constraint. Furthermore, the milling of the first metal shell 5 and the second outer shell uses a milling cutter of the process limit value, resulting in a 0.05mm radius fillet on the inner right-angled edge of the vertical section during machining.

[0052] In another embodiment, such as Figure 2 As shown, the first metal shell 5 and the second outer shell are also provided with pin hole assembly 6, and the first metal shell 5 and the second outer shell are respectively provided with clamping holes 7 for bolts to pass through. The pin hole assembly 6 includes at least one pin and a corresponding pin hole, which is used for precise positioning during mold closing, ensuring that the cavity edges of the upper and lower outer shells are accurately aligned and avoiding gaps. The bolt is inserted into the clamping hole 7 and tightened to apply a uniform clamping force, so that the upper and lower outer shells fit tightly together, avoiding gaps between the cavities and thus introducing discontinuities at the boundary.

[0053] In this embodiment, the dimensions of the aforementioned circular polarizer were precisely designed using the three-dimensional electromagnetic simulation software CST Studio Suite. Furthermore, to facilitate verification of the terahertz circular polarizer's performance, it was simulated in the 170–260 GHz frequency band. The simulation results are as follows: Figure 3 , Figure 4 As shown, within the operating frequency band of 172–260 GHz, the phase difference of the orthogonal modes is within 90 ± 5°, and the amplitude difference of the orthogonal modes is within 0.1 dB across the entire frequency band. The insertion loss at the input port is extremely small, greater than -0.1 dB, and the return loss is basically below -20 dB across the entire frequency band. Therefore, it can be concluded that the terahertz circular polarizer provided in this embodiment can achieve excellent circular polarization performance, and the overall structure of the device is simple, easy to process, small in size, and easy to integrate into the antenna feeding system.

[0054] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high-performance, compact terahertz circular polarizer based on integrated diagonal ridge patterns, characterized in that, include: A metal shell, wherein a cavity is provided inside the metal shell, and both ends of the cavity penetrate the metal shell; Square waveguide (1), the cavity forms the square waveguide (1), and square ridges (2) are provided on two opposite ridges along the length direction of the square waveguide. The first corner corrugated section is disposed on the square ridge (2); The second corner corrugated segment is disposed on two other ridges along the length direction of the square waveguide, and the first corner corrugated segment and the second corner corrugated segment are offset from each other along the length direction of the square waveguide.

2. The high-performance compact terahertz circular polarizer based on integrated diagonal ridges according to claim 1, characterized in that, The first corner corrugated segment includes a plurality of first corner corrugations (3), and the plurality of first corner corrugations (3) are evenly arranged along the length direction of the square ridge (2); The second corner corrugated segment includes a plurality of second corner corrugations (4), which are evenly arranged along the length direction of the square waveguide. The first corner corrugation (3) and the second corner corrugation (4) are both connected to the square waveguide.

3. A high-performance compact terahertz circular polarizer based on integrated diagonal ridges according to claim 2, characterized in that: Both the first angular corrugation (3) and the second angular corrugation (4) are L-shaped.

4. A high-performance compact terahertz circular polarizer based on integrated diagonal ridges according to claim 2, characterized in that, The two ends of the first corner corrugation (3) extend to half the position of the surface corresponding to the square waveguide, and the two ends of the second corner corrugation (4) also extend to half the position of the surface corresponding to the square waveguide.

5. A high-performance compact terahertz circular polarizer based on diagonal ridge integration according to any one of claims 1-4, characterized in that, The metal shell includes a first metal shell (5) and a second outer shell. The first metal shell (5) and the second outer shell are respectively provided with a first cavity (8) and a second cavity. The cavity is composed of the first cavity (8) and the second cavity.

6. A high-performance compact terahertz circular polarizer based on integrated diagonal ridges according to claim 5, characterized in that, The first metal shell (5) and the second outer shell are also provided with pin hole assembly (6), and the first metal shell (5) and the second outer shell are respectively provided with clamping holes (7) for bolts to pass through.

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