Spherical cavity broadband dual-polarization waveguide antenna

Abstract

The present invention provides a spherical cavity broadband dual-polarized waveguide antenna, comprising a spherical metal shell and a circular waveguide metal shell connected to the spherical metal shell, the spherical metal shell having a spherical resonant cavity, the circular waveguide metal shell having a circular waveguide, the spherical metal shell having a cross slot extending therethrough, the cross slot comprising two orthogonally arranged elliptical slots, one end of the spherical resonant cavity being the cross slot, and the other end of the spherical resonant cavity being connected to the circular waveguide. The spherical cavity broadband dual-polarized waveguide antenna provided by the present invention achieves broadband high-gain radiation performance by only using one slotted structure in each polarization direction by providing two orthogonal elliptical slots on the spherical resonant cavity, without requiring an additional enabling structure for extending the bandwidth of the antenna, thereby ensuring that the slotted structure of the antenna is simple and easy to process, has high mechanical strength, and has good compatibility with 3-D printing processes, and helps to improve the molding quality of the integrated additive manufacturing of the antenna.

Description

Technical Field

[0001] The invention belongs to the technical field of microwave antennas, and in particular relates to a spherical cavity broadband dual-polarization waveguide antenna. Background Art

[0002] Dual-polarized antennas can simultaneously transmit and receive linearly polarized signals in two mutually orthogonal directions, saving the number of antennas in a single communication system. They are a type of antenna that improves the frequency reuse capability of communication systems. In millimeter-wave communication systems, in order to withstand large transmit and receive powers, dual-polarized antennas are mostly implemented with waveguide transmission line architectures, which have the advantages of low RF loss, high antenna efficiency, high mechanical strength, and high power capacity. In traditional technologies, dual-polarized waveguide antennas mainly have two radiating unit structures: slots and horns. The former realizes antennas in two polarization directions by opening strip grooves on the waveguide radiating surface, and then splicing and assembling them, or directly opening cross grooves or symmetrical radiating apertures on the waveguide radiating surface. The latter is realized by dual-polarized horns. Traditional waveguide slot antennas are resonant antennas with narrow bandwidths, and often require multi-stage coupling feeding and other methods to expand the antenna bandwidth as much as possible. This makes the cavity structure of the waveguide antenna complex, with many layers during processing and a large number of assembly parts. In large antenna arrays, this traditional structure has many fastening points, a large assembly workload, and difficult to control assembly errors. It is also heavy, which is not conducive to the lightweighting of the front end of satellite, airborne, and radar communication systems. Traditional waveguide horn antennas are traveling wave antennas with wide bandwidths and high gain, but they have large calibers and volumes, which are not conducive to the miniaturization of the front end of communication systems.

[0003] In recent years, with the advancement of additive manufacturing technology, the processing difficulty of spherical resonant cavities has been greatly reduced, and they have been applied to waveguide antennas and waveguide filters. By utilizing the high quality factor, structural symmetry and multi-mode characteristics of the spherical resonant cavity, low-loss filters and broadband high-gain antennas can be realized. In the prior art, the broadband high-gain radiation performance of the waveguide line polarized antenna can be achieved by opening a plurality of parallel rectangular circumferential grooves on the shell of the spherical resonant cavity, but too many grooves will cause the mechanical strength of the grooved structure to decrease significantly, and it is easy to deform and break; moreover, the design method of opening multiple grooves is not suitable for dual-polarized antennas, because dual polarization requires grooves to be opened in two polarization directions. On the other hand, the structure of the traditional rectangular waveguide dual-polarized antenna is compatible with the computer numerical control (CNC) milling process, but not compatible with the 3-D printing process. If these traditional structures are directly 3-D printed, the quality of the antenna molding is defective and the post-processing is difficult. Summary of the invention

[0004] The purpose of the embodiments of the present invention is to provide a spherical cavity broadband dual-polarized waveguide antenna to solve the technical problem in the prior art that a spherical resonant cavity has multiple grooves in two polarization directions and cannot ensure the mechanical strength of the structure (or even the structure cannot be realized), making it difficult to achieve broadband high-gain dual-polarized radiation performance of the spherical resonant cavity.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: to provide a spherical cavity broadband dual-polarization waveguide antenna, comprising a spherical metal shell and a circular waveguide metal shell connected to the spherical metal shell, the spherical metal shell having a spherical resonant cavity, the circular waveguide metal shell having a circular waveguide, the spherical metal shell having a cross groove extending therethrough, the cross groove comprising two orthogonally arranged elliptical grooves, one end of the spherical resonant cavity being the cross groove, the other end of the spherical resonant cavity being connected to the circular waveguide, and the central axis of the cross groove coincides with the central axis of the circular waveguide.

[0006] Optionally, the major axes of the two elliptical grooves are the same in length, and the minor axes of the two elliptical grooves are the same in length.

[0007] Optionally, the cross grooves are arranged in a centrally symmetrical manner.

[0008] Optionally, the connection between the spherical resonant cavity and the circular waveguide is a circular coupling window, one end of the circular waveguide away from the circular coupling window is a circular waveguide port, and the diameter of the circular coupling window is smaller than the diameter of the circular waveguide port.

[0009] Optionally, the radius of the spherical resonant cavity is r 0 , then the major axis length of the elliptical groove is 0.8r 0 To r 0 , the minor axis length of the elliptical groove is 0.3r 0 To 0.5r 0 .

[0010] Optionally, the radius of the connection between the spherical resonant cavity and the circular waveguide is 0.6r 0 To 0.8r 0 .

[0011] Optionally, the diameter of the circular waveguide gradually increases from the spherical resonant cavity to a direction away from the spherical resonant cavity, and the radius of the circular waveguide at one end away from the spherical resonant cavity is 0.9r 0 To 1.1r 0 .

[0012] The beneficial effect of the spherical cavity broadband dual-polarized waveguide antenna provided by the present invention is that compared with the prior art, the spherical cavity broadband dual-polarized waveguide antenna provided by the present invention, by opening two orthogonal elliptical slots on the spherical resonant cavity, enables the antenna to achieve broadband high-gain radiation performance by only using one slot structure in each polarization direction, without the need for an additional enabling structure for expanding the antenna bandwidth, thereby ensuring that the antenna slot structure is simple and easy to process, has high mechanical strength, and has good compatibility with 3-D printing processes, and can effectively avoid deformation caused by residual stress when 3-D printing traditional slot structures, thereby helping to improve the molding quality of the antenna integrated additive manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0014] Figure 1 A three-dimensional structural diagram of a spherical cavity broadband dual-polarization waveguide antenna provided by an embodiment of the present invention;

[0015] Figure 2 A three-dimensional half-section view of a spherical cavity broadband dual-polarization waveguide antenna provided by an embodiment of the present invention;

[0016] Figure 3 A three-dimensional structural diagram of a dual-polarization transition waveguide antenna for performing a radio frequency performance test in one polarization direction of the spherical cavity broadband dual-polarization waveguide antenna provided by an embodiment of the present invention;

[0017] Figure 4 for Figure 3 A three-dimensional half-section view of

[0018] Figure 5 The simulated and measured port reflection coefficient (S) of the spherical cavity dual-polarized waveguide antenna provided in the embodiment of the present invention 11 )curve;

[0019] Figure 6 The simulated and measured gain curves of the spherical cavity dual-polarized waveguide antenna provided by the embodiment of the present invention;

[0020] Figure 7 A simulated total efficiency curve of the spherical cavity dual-polarized waveguide antenna provided by an embodiment of the present invention;

[0021] Figure 8 shows the simulated and measured normalized radiation patterns of the spherical cavity dual-polarized waveguide antenna provided in an embodiment of the present invention, wherein Figure 8(a) and Figure 8(b) are the E-plane and H-plane patterns at 30 GHz, respectively, Figure 8(c) and Figure 8(d) are the E-plane and H-plane patterns at 34 GHz, respectively, and Figure 8(e) and Figure 8(f) are the E-plane and H-plane patterns at 38 GHz, respectively.

[0022] Among them, the reference numerals in the figure are:

[0023] 1-spherical metal shell; 10-spherical resonant cavity; 11-cross groove; 111-elliptical groove; 2-circular waveguide metal shell; 20-circular waveguide; 21-circular coupling window; 22-circular waveguide port; 3-transition waveguide; 4-waveguide flange; 41-through hole; 42-rectangular waveguide port. DETAILED DESCRIPTION

[0024] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0025] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0026] It should be understood that the orientation or position relationship indicated by terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0027] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0028] The spherical cavity broadband dual-polarization waveguide antenna provided by the embodiment of the present invention is now described.

[0029] See also Figure 1 and Figure 2 , Figure 1 A three-dimensional structural diagram of a spherical cavity dual-polarized waveguide antenna provided in an embodiment of the present invention, Figure 2 A three-dimensional half-section view of a spherical cavity dual-polarized waveguide antenna provided in an embodiment of the present invention. The spherical cavity broadband dual-polarized waveguide antenna includes a spherical metal shell 1 and a circular waveguide metal shell 2, and the spherical metal shell 1 and the circular waveguide metal shell 2 are connected to each other. A spherical resonant cavity 10 is provided inside the spherical metal shell 1, and a circular waveguide 20 is provided inside the circular waveguide metal shell 2. Since the spherical metal shell 1 and the circular waveguide metal shell 2 are connected to each other, the spherical resonant cavity 10 and the circular waveguide 20 are coupled and connected, and the coupling connection is a circular coupling window 21, and the end of the circular waveguide 20 away from the circular coupling window 21 is a circular waveguide port 22. The circular waveguide 20 feeds the spherical resonant cavity 10 through the above-mentioned circular coupling window 21, and two mutually orthogonal linear polarized waves can be transmitted simultaneously in the circular waveguide 20.

[0030] A cross groove 11 is provided on the spherical metal shell 1. The cross groove 11 runs through the spherical metal shell 1 and includes two orthogonally arranged elliptical grooves 111. One end of the spherical resonant cavity 10 is the cross groove 11, and the other end of the spherical resonant cavity 10 is coupled to the circular waveguide 20. The major axis and the minor axis of the two elliptical grooves 111 extend in the X direction and the Y direction respectively, and the elliptical groove 111 in each direction is used to transmit and receive signals in a polarization direction orthogonal to the direction.

[0031] The port plane of the circular waveguide 20 has independently transmitted linearly polarized waves in two perpendicular polarization directions, which excite TM waves in their respective polarization directions in the spherical resonant cavity 10. 101 With TM 211 The corresponding modes in each direction are kept orthogonal and do not affect each other. Through two orthogonal elliptical grooves 111, TM 101 With TM 211 The mode radiates effectively, and by adjusting the sizes of the elliptical slot 111 and the circular coupling window 21, broadband and high-gain dual-polarization radiation performance can be achieved.

[0032] The spherical cavity broadband dual-polarized waveguide antenna in the above embodiment, by opening two orthogonal elliptical slots 111 on the spherical resonant cavity 10, enables the antenna to achieve broadband high-gain radiation performance by only using one slot structure in each polarization direction, without the need for an additional enabling structure to expand the antenna bandwidth, thereby ensuring that the mechanical strength of the antenna slot structure is sufficiently high; by performing an elliptical shaping design on the cross slot 11, the compatibility of the antenna structure with the 3-D printing process is significantly improved, and deformation caused by residual stress when 3-D printing traditional slot structures can be effectively avoided; the antenna structure is simple, which improves the quality of the antenna's support-free integrated manufacturing using additive manufacturing technology.

[0033] In one embodiment of the present invention, see Figure 1 and Figure 2 , the central axis of the cross slot 11 coincides with the central axis of the circular waveguide 20. The center point of the intersection of the two elliptical slots 111 is located on the central axis of the cross slot 11, and the central axis of the cross slot 11 passes through the center of the spherical resonant cavity 10. When the central axis of the cross slot 11 coincides with the central axis of the circular waveguide 20, the cross slot 11 and the circular waveguide 20 are arranged opposite to each other, which can ensure better radiation performance and polarization isolation.

[0034] In one embodiment of the present invention, see Figure 1 and Figure 2 The lengths of the major axes of the two elliptical slots 111 are the same, and the lengths of the minor axes of the two elliptical slots 111 are also the same, that is, the sizes of the two elliptical slots 111 are exactly the same. In this way, the radiation performance in the two polarization directions can be made the same.

[0035] In one embodiment of the present invention, see Figure 1 and Figure 2 The cross slot 11 is centrally symmetrically arranged, that is, the centers of the two elliptical slots 111 overlap, so that the cross slot 11 is centrally symmetrically arranged. When the central axis of the cross slot 11 coincides with the central axis of the circular waveguide 20, the two elliptical slots 111 can face the circular waveguide 20.

[0036] In one embodiment of the present invention, the circular coupling window 21 and the circular waveguide port 22 are respectively two ends of the circular waveguide 20. Figure 2 The diameters of the circular coupling window 21 and the circular waveguide port 22 are different. The diameter of the circular coupling window 21 is smaller than the diameter of the circular waveguide port 22, so that the circular waveguide 20 is truncated cone-shaped. The truncated cone-shaped structure replaces the steps formed by the intersection of the cavity structure at the traditional waveguide coupling window. First, it avoids the use of supporting materials near the waveguide coupling window during 3-D printing. Second, it realizes a smooth internal contour compatible with 3-D printing, thereby ensuring the process quality of antennas made using 3-D printing technology.

[0037] See also Figure 3 and Figure 4 , Figure 3 A 3D structural diagram of a dual-polarization transition waveguide antenna for testing the radio frequency performance in one polarization direction of a spherical cavity dual-polarization waveguide antenna provided in an embodiment of the present invention, Figure 4 for Figure 3 A three-dimensional half-section view. In order to measure the radio frequency performance of a spherical cavity dual-polarization waveguide antenna provided in an embodiment of the present invention, a circular waveguide-rectangular waveguide transition is used to transition the antenna's feed port from the circular waveguide port 22 to the rectangular waveguide port 42. For ease of description, the circular waveguide-rectangular waveguide transition is referred to as a transition waveguide 3. A waveguide flange 4 is provided at one end of the rectangular waveguide port 42 of the transition waveguide 3, and a plurality of through holes 41 are provided on the waveguide flange 4 for connection with an external circuit assembly. The transition waveguide 3 is a waveguide with a smooth inner contour, which is used to realize the TE transmitted in the circular waveguide 20. 11 mode and TE propagation in rectangular waveguide 10 Mode conversion. TE at port 42 of the rectangular waveguide 10 The polarization direction of the mode electric field is parallel to one of the polarization directions of the dual-polarized antenna. Note that Figure 3 In the dual-polarization transition waveguide antenna, except for the waveguide flange 4, the entire metal shell has a smoothly connected curved surface profile inside and outside, and such a curved surface profile is obtained by rounding the edges.

[0038] The resonant frequency of the mode radiated by the spherical cavity broadband dual-polarization waveguide antenna in the present invention is determined by the radius of the spherical resonant cavity 10. The operating frequency band of the waveguide antenna can be adjusted by changing the radius of the spherical resonant cavity 10. For example, the center frequency of the antenna operating frequency band is 33 GHz, and the radius of the spherical cavity at this frequency corresponds to 5 mm.

[0039] In one embodiment of the present invention, if the radius of the spherical resonant cavity 10 is r 0 , then the major axis of the elliptical groove 111 is 0.8r 0 To r 0 , the minor axis of the elliptical groove 111 is 0.3r 0 To 0.5r 0 The radius of the connection between the spherical resonator 10 and the circular waveguide 20 (radius of the circular coupling port) is 0.6r 0 To 0.8r 0 The circular waveguide 20 is in the shape of a truncated cone, and the radius of the circular waveguide 20 away from the end of the spherical resonant cavity 10 (the radius of the circular waveguide port 22) is 0.9r 0 To 1.1r 0 .

[0040] Specifically, for such a spherical cavity dual-polarized waveguide antenna operating in the Ka band, a set of preferred dimensions are: the radius of the spherical resonant cavity 10 is 5 mm, the radius of the circular coupling window 21 is 4 mm, and the radius of the circular waveguide port 22 is 5 mm; the length of the circular waveguide 20 is 9 mm; the lengths of the major axis and minor axis of the elliptical groove 111 in each polarization direction are 4.5 mm and 2 mm, respectively; the length of the transition waveguide 3 is 20 mm; the waveguide flange 4 is the standard flange size in the national standard code BJ320, wherein the wide side and narrow side lengths of the rectangular waveguide port 42 are 7.112 mm and 3.556 mm, respectively; and the thickness of the metal shell is set between 2 mm and 3 mm.

[0041] See also Figure 5 To Figure 8, Figure 5 The simulated and measured port reflection coefficient (S) of a spherical cavity dual-polarized waveguide antenna provided in an embodiment of the present invention 11 )curve, Figure 6 The simulated and measured gain curves of a spherical cavity dual-polarized waveguide antenna provided in an embodiment of the present invention are as follows: Figure 7 FIG. 8 is a simulated total efficiency curve of a spherical cavity dual-polarized waveguide antenna provided in an embodiment of the present invention. FIG. 9 is a simulated and measured normalized radiation pattern of a spherical cavity dual-polarized waveguide antenna provided in an embodiment of the present invention, wherein FIG. 8(a) is the E-plane pattern at 30 GHz, FIG. 8(b) is the H-plane pattern at 30 GHz, FIG. 8(c) is the E-plane pattern at 34 GHz, FIG. 8(d) is the H-plane pattern at 34 GHz, FIG. 8(e) is the E-plane pattern at 38 GHz, and FIG. 8(f) is the H-plane pattern at 38 GHz.

[0042] The simulated operating frequency range of a spherical cavity dual-polarized waveguide antenna provided by the embodiment of the present invention is 26.5-39.2 GHz, and the simulated in-band reflection coefficient is less than -10 dB. Figure 5 It can be seen that the simulated relative bandwidth of the antenna can reach 38.7%, the simulated in-band gain (including transition waveguide) is 7.2-9.3dBi, and the simulated in-band total efficiency is better than 89%. Within the working bandwidth, the antenna has good radiation performance in both polarization directions and no distortion in the pattern.

[0043] In order to experimentally verify the RF performance of a spherical cavity dual-polarization waveguide antenna provided by an embodiment of the present invention, a high-precision multi-nozzle inkjet 3-D printing process is used to manufacture the spherical cavity dual-polarization waveguide antenna with photosensitive resin, and copper is electroplated on the surface of the 3-D printed resin structure to complete the metallization of the entire shell surface. The geometrically shaped antenna shell does not require any support material during the 3-D printing process. Figure 5As shown in Figure 8, the simulation and measurement results of the antenna are in good agreement. The antenna reflection coefficient measured in the range of 26.5–39 GHz is less than -10 dB, the measured relative bandwidth of the antenna is 38.2%, and the measured in-band gain is 7–9 dBi. The antenna can maintain good and stable dual-polarization directional radiation in the band. Figure 3 and Figure 4 The measured antenna cross-polarization ratio is better than 16dB in the polarization direction shown.

[0044] In the embodiments provided by the present invention, it should be understood that, first, how to follow the design concept of geometric shaping to shape the metal shell and radiation structure of the traditional waveguide antenna, and how to use the multi-mode characteristics of the spherical cavity to achieve broadband, high-gain, stable dual-polarization radiation performance with the simplest possible slot structure are the core technical problems solved by the present invention; second, the slot structure and its size used for radiation are only schematic, not unique, and are only a better achievable structure. Other equivalent radiation slots can also be realized according to the design principle; third, the antenna structure is shaped and designed to be suitable for a variety of non-metallic / metallic 3-D printing processes and printing materials, and the structural design method has strong universality.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A spherical cavity broadband dual-polarization waveguide antenna, characterized in that: The invention comprises a spherical metal shell and a circular waveguide metal shell connected to the spherical metal shell, wherein the spherical metal shell has a spherical resonant cavity, the circular waveguide metal shell has a circular waveguide, the spherical metal shell is provided with a through cross slot, the cross slot comprises two orthogonally arranged elliptical slots, one end of the spherical resonant cavity is the cross slot, the other end of the spherical resonant cavity is connected to the circular waveguide, the central axis of the cross slot coincides with the central axis of the circular waveguide; the radius of the spherical resonant cavity is r0, the major axis length of the elliptical slot is 0.8r0 to r0, and the minor axis length of the elliptical slot is 0.3r0 to 0.5r0, so as to improve the gain and bandwidth.

2. The spherical cavity broadband dual-polarization waveguide antenna according to claim 1, characterized in that: The major axes of the two elliptical grooves are the same in length, and the minor axes of the two elliptical grooves are the same in length.

3. The spherical cavity broadband dual-polarization waveguide antenna according to claim 1, characterized in that: The cross grooves are arranged in a centrally symmetrical manner.

4. The spherical cavity broadband dual-polarization waveguide antenna according to claim 1, characterized in that: The connection between the spherical resonant cavity and the circular waveguide is a circular coupling window, one end of the circular waveguide away from the circular coupling window is a circular waveguide port, and the diameter of the circular coupling window is smaller than the diameter of the circular waveguide port.

5. The spherical cavity broadband dual-polarization waveguide antenna according to claim 1, characterized in that: The radius of the connection between the spherical resonant cavity and the circular waveguide is 0.6r0 to 0.8r0.

6. The spherical cavity broadband dual-polarization waveguide antenna according to claim 5, characterized in that: The diameter of the circular waveguide gradually increases from the spherical resonant cavity to a direction away from the spherical resonant cavity, and the radius of the circular waveguide at one end away from the spherical resonant cavity is 0.9r0 to 1.1r0.

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