Millimeter wave circularly polarized ridge gap waveguide antenna

Abstract

The invention discloses a millimeter wave circular polarization ridge gap waveguide antenna. The waveguide antenna comprises a feed waveguide layer, a waveguide gap layer, a grating lobe suppressor, a polarization converter and a radiation cavity layer which are sequentially stacked from bottom to top. The waveguide antenna adopts an interdigital ridge structure, so that electromagnetic wave leakage radiation can be effectively inhibited, the stability of the working mode of the antenna unit is ensured, and the isolation of the antenna in a large-scale array is enhanced; the feed waveguide layer and the waveguide slot layer are spliced to form the interdigital ridge structure, the production and assembly process is simple, the welding process is omitted, and the production cost is reduced; left-hand circular polarization or right-hand circular polarization can be switched on the polarization converter by changing the orientation of the cross-type gap. By feeding from the two ends of the feed waveguide layer, a dual-circular-polarization working mode can also be realized; by adjusting the size of each slot on the waveguide slot layer, the flexibility of grating lobe suppression can be improved, and the side lobe level of the antenna can be reduced. The invention relates to the technical field of antennas.

Description

Technical Field

[0001] This application relates to the field of antenna technology, and particularly to a millimeter-wave circularly polarized ridge gap waveguide antenna. Background Art

[0002] Waveguide slot antennas have the characteristics of high radiation efficiency, compact structure, and easy implementation of low sidelobes, and are widely used in communication systems such as satellites, radars, and remote sensing. However, traditional waveguide antennas achieve circular polarization by adding a polarization rotator to a single slot. Such circularly polarized antennas have a narrow bandwidth and a high profile. In addition, the waveguide cavity and the radiation slot layer must be processed separately. During the assembly process of the antenna into a complete component, it is difficult for the cavity and the radiation layer to fit perfectly, resulting in electromagnetic energy leakage. Especially in large-scale arrays, the performance of the array antenna will deteriorate sharply, leading to a sharp decline in the communication quality of the system.

[0003] As a new type of electromagnetic bandgap transmission structure, when the gap between the radiation layer and the electromagnetic bandgap surface is less than one-quarter wavelength, electromagnetic waves cannot propagate in it. Compared with a full-metal waveguide cavity, the upper and lower layers do not need to fit perfectly to prevent electromagnetic energy leakage. However, in waveguide antennas in the millimeter-wave and terahertz frequency bands, etc., the size of the periodic ridges is small and the ridge spacing is small. The existing processing accuracy is limited, it is difficult to ensure the integrity of the structure, and the tolerance is small, resulting in difficulty in large-scale mass production of antennas.

[0004] Therefore, a new type of ridge gap waveguide structure is needed that can suppress electromagnetic wave leakage and improve production efficiency within a specified operating frequency band. Summary of the Invention

[0005] This application aims to solve at least one of the technical problems existing in the prior art. For this purpose, this application proposes a millimeter-wave circularly polarized ridge gap waveguide antenna, which can expand the circular polarization bandwidth of the millimeter-wave antenna, improve the freedom of large-scale mass production of the millimeter-wave antenna, and reduce the sidelobe level of the millimeter-wave antenna.

[0006] The millimeter-wave circularly polarized ridge gap waveguide antenna according to the first aspect embodiment of this application includes a feed waveguide layer, a waveguide slot layer, a grating lobe suppressor, a polarization converter, and a radiation cavity layer stacked in sequence from bottom to top, wherein:

[0007] The feed waveguide layer includes a first interdigital ridge and a central ridge. The central ridge extends along the x direction. The first interdigital ridge is divided into two groups and symmetrically arranged on both sides of the central ridge. The first interdigital ridge is arranged in an array along the x direction;

[0008] The waveguide slot layer is provided with a second interdigital ridge. The second interdigital ridge is arranged staggered with the first interdigital ridge and there is a gap between them. The waveguide slot layer is provided with a plurality of first slots arranged along the x direction;

[0009] The grating lobe suppressor is provided with a second slit that can expose the first slit;

[0010] The polarization converter is provided with a plurality of cross-shaped slits that form an angle θ with the x-direction, where θ is an acute angle or an obtuse angle;

[0011] The radiation cavity layer is provided with a third slit that can expose the cross-shaped slit, and symmetric steps are arranged on both sides of the radiation cavity layer, and choke grooves are arranged in the steps.

[0012] The millimeter-wave circularly polarized ridge gap waveguide antenna according to the embodiment of the present application has at least the following beneficial effects: The waveguide antenna adopts an interdigital ridge structure, which can effectively suppress the leakage radiation of electromagnetic waves, not only ensuring the stability of the working mode of the antenna unit itself, but also enhancing the isolation degree of the antenna in a large-scale array; The feeding waveguide layer and the waveguide slit layer are spliced with each other to form an interdigital ridge structure, and the production and assembly processes are simple, the welding process is omitted, and the production cost is reduced; On the polarization converter, by changing the orientation of the cross-shaped slit, the left-handed circular polarization or the right-handed circular polarization can be switched, and the dual circular polarization working mode can also be realized; By adjusting the sizes of the slits on the waveguide slit layer, the flexibility of grating lobe suppression can be increased, and the antenna side lobe level can be reduced.

[0013] According to some embodiments of the present application, the gap width between the first interdigital ridge and the second interdigital ridge is one-sixteenth of the wavelength of the center frequency.

[0014] According to some embodiments of the present application, non-uniformly arranged short ridges are arranged on the side surface of the central ridge, and a hollow feeding waveguide port is arranged in the middle of the central ridge.

[0015] According to some embodiments of the present application, the first slit is distributed in a Taylor distribution or a Chebyshev distribution along the x-direction.

[0016] According to some embodiments of the present application, the cross-shaped slit is composed of a wide slit and a narrow slit, and the wide slit and the narrow slit are perpendicular to each other.

[0017] According to some embodiments of the present application, the third slit is in a hexagon shape that is centrosymmetric, and the shorter side of the third slit corresponds to the narrow slit.

[0018] According to some embodiments of the present application, the depth of the choke groove is one-fourth of the wavelength of the center frequency.

[0019] According to some embodiments of the present application, both the first interdigital ridge and the second interdigital ridge are rectangular strip structures, and a column of the first interdigital ridges and a column of the second interdigital ridges are respectively arranged on both sides of the central ridge.

[0020] According to some embodiments of the present application, both the first interdigital ridge and the second interdigital ridge are square structures, and three columns of the first interdigital ridges and three columns of the second interdigital ridges are respectively arranged on both sides of the central ridge.

[0021] According to some embodiments of the present application, both the first interdigital ridge and the second interdigital ridge are cylindrical structures, and three columns of the first interdigital ridges and three columns of the second interdigital ridges are respectively arranged on both sides of the central ridge.

[0022] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present application. Description of the Drawings

[0023] The drawings are used to provide a further understanding of the technical solutions disclosed in the present application, and constitute a part of the specification. Together with the embodiments disclosed in the present application, they are used to explain the technical solutions of the present disclosure, and do not constitute a limitation to the technical solutions disclosed in the present application.

[0024] Figure 1 It is a disassembly diagram of the millimeter-wave circularly polarized ridge gap waveguide antenna of the present application;

[0025] Figure 2 It is a three-dimensional view of the feeding waveguide layer in the millimeter-wave circularly polarized ridge gap waveguide antenna of the present application;

[0026] Figure 3 It is a combined schematic diagram of the feeding waveguide layer and the waveguide slot layer in the millimeter-wave circularly polarized ridge gap waveguide antenna of the present application;

[0027] Figure 4 It is a schematic diagram of the polarization converter in the millimeter-wave circularly polarized ridge gap waveguide antenna of the present application adopting the left-handed working mode;

[0028] Figure 5 It is a schematic diagram of the polarization converter in the millimeter-wave circularly polarized ridge gap waveguide antenna of the present application adopting the right-handed working mode;

[0029] Figure 6 It is a partial enlarged view of the cross-shaped slot in the millimeter-wave circularly polarized ridge gap waveguide antenna of the present application;

[0030] Figure 7 It is a top view of the radiation cavity layer in the millimeter-wave circularly polarized ridge gap waveguide antenna of the present application;

[0031] Figure 8 It is the dispersion curve of the interdigital ridge in Embodiment 1 of the millimeter-wave circularly polarized ridge gap waveguide antenna of the present application;

[0032] Figure 9 It is the antenna S in Embodiment 1 of the millimeter-wave circularly polarized ridge gap waveguide antenna of the present application 11Variation curve with frequency;

[0033] Figure 10 This is the variation curve of the axial ratio of the antenna with frequency in Embodiment 1 of the millimeter-wave circularly polarized ridge gap waveguide antenna of the present application;

[0034] Figure 11 This is the left-handed circular polarization radiation pattern of the antenna at 28.5 GHz in Embodiment 1 of the millimeter-wave circularly polarized ridge gap waveguide antenna of the present application;

[0035] Figure 12 This is the 3D diagram of the feed waveguide layer in Embodiment 2 of the millimeter-wave circularly polarized ridge gap waveguide antenna of the present application;

[0036] Figure 13 This is the right-handed circular polarization radiation pattern of the antenna at 28.5 GHz in Embodiment 2 of the millimeter-wave circularly polarized ridge gap waveguide antenna of the present application;

[0037] Figure 14 This is the 3D diagram of the feed waveguide layer in Embodiment 3 of the millimeter-wave circularly polarized ridge gap waveguide antenna of the present application.

[0038] Reference numerals: 100 - feed waveguide layer, 110 - first interdigital ridge, 120 - central ridge, 130 - short ridge, 140 - feed waveguide port, 200 - waveguide slot layer, 210 - second interdigital ridge, 220 - first slot, 300 - grating lobe suppressor, 310 - second slot, 400 - polarization converter, 410 - cross-shaped slot, 420 - wide slot, 430 - narrow slot, 500 - radiation cavity layer, 510 - third slot, 520 - step, 530 - choke groove. Detailed implementation manners

[0039] The following details the embodiments of the present application. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present application and should not be construed as a limitation of the present application.

[0040] In the description of the present application, it should be understood that for the orientation description, such as the orientation or positional relationship indicated by up, down, front, back, left, right, etc., is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present application.

[0041] In the description of this application, "several" means more than one, "multiple" means more than two, and understandings such as "greater than", "less than", "exceeding", etc. do not include the corresponding number, while understandings such as "above", "below", "within", etc. include the corresponding number. If there is a description of "first" and "second", it is only for the purpose of distinguishing technical features and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features or implicitly specifying the sequence relationship of the indicated technical features.

[0042] In the description of this application, unless otherwise clearly defined, words such as "set", "installed", "connected", etc. should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above words in this application in combination with the specific content of the technical solution.

[0043] In the description of this application, the description with reference to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0044] Waveguide slot antennas have the characteristics of high radiation efficiency, compact structure, and easy realization of low sidelobes, and are widely used in communication systems such as satellites, radars, and remote sensing. However, traditional waveguide antennas achieve circular polarization by adding a polarization rotator to a single slot. Such circular polarization antennas have a narrow bandwidth and a high profile. In addition, the waveguide cavity and the radiation slot layer must be processed separately. During the assembly process of the complete antenna component, it is difficult for the cavity and the radiation layer to fit perfectly, which will cause electromagnetic energy leakage. Especially in large-scale arrays, it will cause a sharp deterioration in the performance of the array antenna, thus causing a sharp decline in the communication quality of the system.

[0045] As a new type of electromagnetic bandgap transmission structure, when the gap between the radiation layer and the electromagnetic bandgap surface is less than one-quarter wavelength, electromagnetic waves cannot propagate in it. Compared with a full-metal waveguide cavity, the upper and lower layers do not need to fit perfectly to prevent electromagnetic energy leakage. However, on waveguide antennas in millimeter-wave, terahertz frequency bands, etc., the size of the periodic ridges is small, the ridge spacing is small, the existing processing accuracy is limited, it is difficult to ensure the integrity of the structure, and the tolerance is small, resulting in difficulty in large-scale mass production of antennas.

[0046] Therefore, a new type of ridge gap waveguide structure is needed, which can suppress electromagnetic wave leakage and improve production efficiency within a specified operating frequency band.

[0047] In response to this, the present application proposes a millimeter-wave circularly polarized ridge gap waveguide antenna, which can effectively suppress electromagnetic wave leakage radiation, not only ensuring the stability of the working mode of the antenna unit itself, but also enhancing the isolation degree of the antenna in a large-scale array; the feeding waveguide layer 100 and the waveguide slot layer 200 are spliced together to form an interdigital ridge structure, with simple production and assembly processes, omitting the welding process and reducing production costs; on the polarization converter 400, by changing the orientation of the cross-shaped slot 410, the left-handed circular polarization or the right-handed circular polarization can be switched, and the dual circular polarization working mode can also be realized; by adjusting the sizes of the slots on the waveguide slot layer 200, the flexibility of grating lobe suppression can be increased, and the antenna sidelobe level can be reduced.

[0048] Referring to Figure 1 , the millimeter-wave circularly polarized ridge gap waveguide antenna in the present application includes a feeding waveguide layer 100, a waveguide slot layer 200, a grating lobe suppressor 300, a polarization converter 400, and a radiation cavity layer 500 stacked in sequence from bottom to top. Among them, referring to Figure 2 , the feeding waveguide layer 100 includes a first interdigital ridge 110 and a central ridge 120. The central ridge 120 extends along the x direction. The first interdigital ridge 110 is divided into two groups and symmetrically arranged on both sides of the central ridge 120. The first interdigital ridge 110 is arranged in an array along the x direction (in the present application, the x direction is the arrow direction in the figure). The first interdigital ridge 110 can be set to one row, two rows, or multiple rows, and the specific shape of the first interdigital ridge 110 can also be replaced according to actual needs. Referring to Figure 2 , the waveguide slot layer 200 is provided with a second interdigital ridge 210, and the second interdigital ridge 210 is arranged in an interleaved manner with the first interdigital ridge 110 and there is a gap between them.

[0049] It should be noted that the spacing of the first interdigital ridge 110 and the spacing of the second interdigital ridge 210 are maintained at one-quarter wavelength of the center frequency. After the feeding waveguide layer 100 and the waveguide slot layer 200 are spliced together, the spacing between the first interdigital ridge 110 and the second interdigital ridge 210 is maintained at one-sixteenth wavelength of the center frequency. Such a design can effectively suppress electromagnetic wave leakage radiation, not only ensuring the stability of the working mode of the antenna unit itself, but also enhancing the isolation degree of the antenna in a large-scale array.

[0050] Furthermore, both the first interdigital ridge 110 and the second interdigital ridge 210 are made of metal and are respectively fixed on the feeding waveguide layer 100 and the waveguide slot layer 200 by an insertion method. Since the structures of the interdigital ridges are dispersedly arranged on the feeding waveguide layer 100 and the waveguide slot layer 200, the spacing of the interdigital ridges in the single-layer structure is large, which is more conducive to the processing of small-size waveguide antennas. Moreover, the gaps between the first interdigital ridges 110 and between the second interdigital ridges 210 reach one-quarter wavelength of the center frequency, which is beneficial to the layout of large-scale antenna arrays.

[0051] Specifically, the feeding waveguide layer 100 is provided with grooves for accommodating the first interdigital ridge 110 and the central ridge 120. The top of the first interdigital ridge 110 is flush with the top of the feeding waveguide layer 100, and the height of the central ridge 120 is less than that of the interdigital ridge 110. When the waveguide slot layer 200 is installed on the feeding waveguide layer 100, the second interdigital ridge 210 can extend into the groove and jointly form an interdigital ridge structure with the first interdigital ridge 110. The feeding waveguide layer 100 and the waveguide slot layer 200 do not need to be fully adhered, eliminating the soldering process. This not only improves the freedom of antenna mass production and has greater tolerance, but also reduces the antenna equipment process and lowers the antenna production cost.

[0052] Furthermore, in the feeding waveguide layer 100, short ridges 130 are unevenly arranged on the side surface of the central ridge 120, extending towards the side surface of the central ridge 120 but not contacting the first interdigital ridge 110. The height of the short ridges 130 is the same as that of the central ridge 120. After the feeding waveguide layer 100 and the waveguide slot layer 200 are joined, there is a gap between the tops of the central ridge 120 and the short ridges 130 and the waveguide slot layer 200. Specifically, there are multiple short ridges 130, and a vertical symmetry axis is set at the center of the central ridge 120, and each short ridge 130 is symmetrically arranged with respect to this symmetry axis. The introduction of the short ridges 130 can improve the antenna impedance matching performance. In addition, a hollow feeding waveguide port 140 is provided in the middle of the central ridge 120 for guiding radio waves to enter.

[0053] The waveguide slot layer 200 is provided with a plurality of first slots 220 arranged along the x direction. The sizes and spacings of these first slots 220 are different, and the shapes are rectangular. Each first slot 220 is centrosymmetrically distributed about the center of the waveguide slot layer 200. It should be noted that in some embodiments, the first slots 220 are distributed in a Taylor distribution or a Chebyshev distribution along the x direction to achieve the low sidelobe performance of the antenna.

[0054] Since the adjacent slot spacing of the first slots 220 in the waveguide slot layer 200 reaches one wavelength, grating lobes will inevitably appear in the antenna pattern. At the same time, in order to ensure the stability of the antenna working mode, the adjustment range of the length and width of the first slots 220 is limited. Therefore, a grating lobe suppressor 300 needs to be introduced. The grating lobe suppressor 300 is provided with a plurality of second slots 310 opened along the x direction. The second slots 310 correspond to the first slots 220, and the length and width of the second slots 310 are both larger than those of the first slots 220, so that the second slots 310 on the grating lobe suppressor 300 can expose the first slots 220 on the waveguide slot layer 200.

[0055] To achieve the circular polarization working mode, a polarization converter 400 is provided on the grating lobe suppressor 300. Refer to Figure 4, the polarization converter 400 is provided with a plurality of cross-shaped slits 410 arranged in the x direction with unequal intervals, and the body axes of the respective cross-shaped slits 410 form an angle θ with the x direction. In some embodiments, referring to Figure 4 , θ is an acute angle; in other embodiments, referring to Figure 5 , θ is an obtuse angle. By changing the magnitude of θ, the orientation of each cross-shaped slit 410 can be adjusted, thereby changing the circular polarization rotation direction. For example, in the present embodiment, when θ is an acute angle, the present antenna unit operates in a left-handed circular polarization mode; when θ is an obtuse angle, the present antenna unit operates in a right-handed circular polarization mode.

[0056] It is easily understood that when signals are introduced from both ends of the feed waveguide layer 100 respectively, the working mode of one port is the left-handed circular polarization working mode, and the working mode of the other port is the right-handed circular polarization working mode. The antenna unit forms a dual circular polarization antenna, which can exhibit significant advantages in coping with the shortage of spectrum resources and improving the signal quality and stability.

[0057] Furthermore, referring to Figure 6 , the cross-shaped slit 410 is composed of a wide slit 420 and a narrow slit 430. The width of the wide slit 420 is greater than the width of the narrow slit 430, and the wide slit 420 and the narrow slit 430 are perpendicular to each other. By controlling the size of the cross-shaped slit 410 and the thickness of the polarization converter 400, two electric fields with equal amplitudes and orthogonal phases can be obtained on the upper surface of the polarization converter 400, and then the synthesized electric field can achieve the circular polarization performance of the antenna.

[0058] In order to expand the antenna axial ratio bandwidth and the spatial axial ratio, a radiation cavity layer 500 is provided on the upper surface of the polarization converter 400. The height of the radiation cavity layer 500 is half of the wavelength of the center frequency. Referring to Figure 7 , the radiation cavity layer 500 is provided with a third slit 510 that can expose the cross-shaped slit 410. The centers of the respective third slits 510 correspond to the centers of the respective cross-shaped slits 410 one by one. In order to improve the antenna beam width and the multipath suppression effect, steps 520 are provided on both sides of the radiation cavity layer 500. The steps 520 are opened downward, and a choke groove 530 is provided thereon. The depth of the choke groove 530 is one-fourth of the wavelength of the center frequency. Regarding the choke groove 530 as an ideal electric wall, when the transverse current of the radiation cavity layer 500 passes through the choke groove 530, an electric field will be generated, and this electric field will induce a vertical current on the electric wall. By combining the horizontal current and the vertical current, the antenna beam width and the spatial axial ratio can be improved.

[0059] It should be noted that the third slit 510 has a centrally symmetric hexagonal shape, which is a non-regular hexagonal structure. The shorter side of the third slit 510 corresponds to the narrow slit 430.

[0060] Specifically, for the specific structure of the present millimeter-wave circularly polarized ridge gap waveguide antenna, the present application proposes three possible embodiments, and corresponding experiments and detections are carried out based on the three embodiments to illustrate their working effects. It should be noted that the present application is not limited to the described embodiments, and various changes made without departing from the purpose of the present application should also be included within the protection scope of the present application.

[0061] Embodiment 1:

[0062] The millimeter-wave circularly polarized ridge gap waveguide antenna in this embodiment includes a feeding waveguide layer 100, a waveguide slot layer 200, a grating lobe suppressor 300, a polarization converter 400, and a radiation cavity layer 500 stacked in sequence from bottom to top. The feeding waveguide layer 100 includes a first interdigital ridge 110 and a central ridge 120. The central ridge 120 extends along the x direction. The first interdigital ridge 110 is divided into two groups and symmetrically arranged on both sides of the central ridge 120. The first interdigital ridge 110 is arranged in an array along the x direction and is equidistantly arranged from each other. The waveguide slot layer 200 is provided with a second interdigital ridge 210. After the waveguide slot layer 200 and the feeding waveguide layer 100 are joined together, the second interdigital ridge 210 and the first interdigital ridge 110 are staggered and there is a gap between them. The waveguide slot layer 200 is provided with a plurality of first slots 220 arranged along the x direction. The sizes and spacings of these first slots 220 are different, and the shapes are rectangular. Each first slot 220 is centrally symmetrically distributed about the center of the waveguide slot layer 200. The grating lobe suppressor 300 is provided with a second slot 310. The second slot 310 corresponds to the first slot 220, and the length and width of the second slot 310 are both greater than the length and width of the first slot 220. Thus, the second slot 310 on the grating lobe suppressor 300 can expose the first slot 220 on the waveguide slot layer 200. The polarization converter 400 is provided with a plurality of cross-shaped slots 410 arranged along the x direction. Each cross-shaped slot 410 forms an angle θ with the x direction, and θ is an acute angle or an obtuse angle. The radiation cavity layer 500 is provided with a third slot 510 that can expose the cross-shaped slots 410. Symmetrical steps 520 are provided on both sides of the radiation cavity layer 500, and choke grooves 530 are provided in the steps 520.

[0063] Based on the above structure, for the millimeter-wave circularly polarized ridge gap waveguide antenna in this embodiment, both the first interdigital ridge 110 and the second interdigital ridge 210 are rectangular strip structures (refer to Figure 1 ), and a column of the first interdigital ridge 110 and a column of the second interdigital ridge 210 are respectively arranged on both sides of the central ridge 120.

[0064] Taking θ as an acute angle and the polarization converter 400 in the left-handed working mode as an example, the millimeter-wave circularly polarized ridge gap waveguide antenna in this embodiment is experimentally tested. The millimeter-wave circularly polarized ridge gap waveguide antenna in this embodiment has a relatively wide bandwidth, high gain, low side lobes, low cross polarization, and a relatively symmetric radiation pattern. Through full-wave electromagnetic simulation analysis, the dispersion curve of the one-dimensional periodic simulation of the interdigital ridge structure is as shown in Figure 8 . The stopband range of the interdigital ridge is 16 to 38 GHz. Within this range, the leakage radiation of electromagnetic waves can be suppressed. The curve of the S 11 of the millimeter-wave circularly polarized ridge gap waveguide antenna versus frequency is as shown in Figure 9 . When the reflection coefficient is less than -10 dB, the bandwidth of the antenna is 26.0 to 30.2 GHz. The axial ratio curve of the millimeter-wave circularly polarized ridge gap waveguide antenna is as shown in Figure 10 . Within the range of 27.2 to 30.0 GHz, the axial ratio is less than 3 dB. The radiation pattern of the millimeter-wave circularly polarized ridge gap waveguide antenna at 28.5 GHz is as shown in Figure 11 . The radiation pattern of the millimeter-wave circularly polarized ridge gap waveguide antenna has good symmetry, the gain is as high as 15.4 dBic, the side lobe level of the antenna is less than -20 dB, and the cross polarization level is less than -20 dB.

[0065] It is easily understandable that θ can also be set as an obtuse angle. At this time, the polarization converter 400 is in the right-handed working mode, and its experimental results are similar to the above experimental results, which will not be elaborated here.

[0066] Embodiment 2:

[0067] The millimeter-wave circularly polarized ridge gap waveguide antenna in this embodiment includes a feeding waveguide layer 100, a waveguide slot layer 200, a grating lobe suppressor 300, a polarization converter 400, and a radiation cavity layer 500 stacked in sequence from bottom to top. The feeding waveguide layer 100 includes a first interdigital ridge 110 and a central ridge 120. The central ridge 120 extends along the x direction. The first interdigital ridge 110 is divided into two groups and symmetrically arranged on both sides of the central ridge 120. The first interdigital ridge 110 is arranged in an array along the x direction and is equidistantly arranged from each other. The waveguide slot layer 200 is provided with a second interdigital ridge 210. After the waveguide slot layer 200 and the feeding waveguide layer 100 are joined together, the second interdigital ridge 210 is staggered with the first interdigital ridge 110 and there is a gap between them. The waveguide slot layer 200 is provided with a plurality of first slots 220 arranged along the x direction. The sizes and spacings of these first slots 220 are different, and the shapes are rectangular. Each first slot 220 is centrosymmetrically distributed about the center of the waveguide slot layer 200. The grating lobe suppressor 300 is provided with a second slot 310. The second slot 310 corresponds to the first slot 220, and the length and width of the second slot 310 are both greater than the length and width of the first slot 220, so that the second slot 310 on the grating lobe suppressor 300 can expose the first slot 220 on the waveguide slot layer 200. The polarization converter 400 is provided with a plurality of cross slots 410 arranged along the x direction. Each cross slot 410 forms an angle θ with the x direction, and θ is an acute angle or an obtuse angle. The radiation cavity layer 500 is provided with a third slot 510 that can expose the cross slots 410. Symmetrical steps 520 are provided on both sides of the radiation cavity layer 500, and choke grooves 530 are provided in the steps 520.

[0068] On the basis of the above structure, in the millimeter-wave circularly polarized ridge gap waveguide antenna in this embodiment, both the first interdigital ridge 110 and the second interdigital ridge 210 are square structures (refer to Figure 12 ), and three columns of first interdigital ridges 110 and three columns of second interdigital ridges 210 are respectively arranged on both sides of the central ridge 120. Further, in the feeding waveguide layer 100, six short ridges 130 are symmetrically arranged on both sides of the feeding waveguide port 140.

[0069] Taking θ as an obtuse angle and the polarization converter 400 as the right-handed working mode as an example, the millimeter-wave circularly polarized ridge gap waveguide antenna in this embodiment is experimentally tested. The millimeter-wave circularly polarized ridge gap waveguide antenna in this embodiment also has a relatively wide bandwidth, high gain, low side lobes, low cross polarization, and a relatively symmetric radiation pattern. The radiation pattern of the antenna at 28.5 GHz is as shown in Figure 13 . The pattern has good symmetry, the gain is as high as 15.5 dBic, the side lobe level of the antenna is less than -20 dB, and the cross polarization level is less than -21 dB.

[0070] Understandably, θ can also be set to an acute angle. In this case, the polarization converter 400 operates in a left-handed mode, and its experimental results are similar to those of the above experiments, which will not be elaborated here.

[0071] Embodiment 3:

[0072] The millimeter-wave circularly polarized ridge gap waveguide antenna in this embodiment includes a feed waveguide layer 100, a waveguide slot layer 200, a grating lobe suppressor 300, a polarization converter 400, and a radiation cavity layer 500 stacked in sequence from bottom to top. The feed waveguide layer 100 includes a first interdigital ridge 110 and a center ridge 120. The center ridge 120 extends along the x direction. The first interdigital ridge 110 is divided into two groups and symmetrically arranged on both sides of the center ridge 120. The first interdigital ridge 110 is arranged in an array along the x direction and is equidistantly arranged from each other. The waveguide slot layer 200 is provided with a second interdigital ridge 210. After the waveguide slot layer 200 is joined with the feed waveguide layer 100, the second interdigital ridge 210 is staggered with the first interdigital ridge 110 and there is a gap between them. The waveguide slot layer 200 is provided with a plurality of first slots 220 arranged along the x direction. The sizes and spacings of these first slots 220 are different, and the shapes are rectangular. Each first slot 220 is centrosymmetrically distributed about the center of the waveguide slot layer 200. The grating lobe suppressor 300 is provided with a second slot 310. The second slot 310 corresponds to the first slot 220, and the length and width of the second slot 310 are both larger than the length and width of the first slot 220. Thus, the second slot 310 on the grating lobe suppressor 300 can expose the first slot 220 on the waveguide slot layer 200. The polarization converter 400 is provided with a plurality of cross-shaped slots 410 arranged along the x direction. Each cross-shaped slot 410 forms an angle θ with the x direction, and θ is an acute angle or an obtuse angle. The radiation cavity layer 500 is provided with a third slot 510 that can expose the cross-shaped slots 410. Symmetrical steps 520 are provided on both sides of the radiation cavity layer 500, and choke grooves 530 are provided in the steps 520.

[0073] Based on the above structure, in the millimeter-wave circularly polarized ridge gap waveguide antenna of this embodiment, both the first interdigital ridge 110 and the second interdigital ridge 210 are cylindrical structures (refer to Figure 14 ), and three columns of first interdigital ridges 110 and three columns of second interdigital ridges 210 are respectively arranged on both sides of the center ridge 120. Further, in the feed waveguide layer 100, six short ridges 130 are symmetrically arranged on both sides of the feed waveguide port 140.

[0074] Taking the case where θ of some of the partially crossed slots 410 in the polarization converter 400 is an acute angle and θ of the other part of the partially crossed slots 410 is an obtuse angle, and the polarization converter 400 is in a dual circular polarization operating mode as an example. The millimeter-wave circularly polarized ridge gap waveguide antenna is fed through two ports and is distributed at both ends of the feed waveguide layer 100. When the operating mode of the first port is left-handed circular polarization, the operating mode of the second port is right-handed circular polarization; conversely, when the operating mode of the first port is right-handed circular polarization, the operating mode of the second port is left-handed circular polarization. In this embodiment, the cylindrical first interdigital ridge 110 and the second interdigital ridge 210 are easier to mold and mass-produce, greatly reducing the production cost. It should be noted that the diameters of the cylindrical first interdigital ridge 110 and the second interdigital ridge 210 in this embodiment are equal to the widths of the square first interdigital ridge 110 and the second interdigital ridge 210 in Embodiment 2. Both ends of the central ridge 120 penetrate the first port and the second port respectively.

[0075] The millimeter-wave circularly polarized ridge gap waveguide antenna in this embodiment can transmit signals in two polarization directions simultaneously, which is equivalent to doubling the transmission channels under the same frequency resources and improving the spectral efficiency. This millimeter-wave circularly polarized ridge gap waveguide antenna can, to a certain extent, offset the influence of multipath fading by using signals in two different polarization directions, improving the stability and reliability of the signals. The dual circular polarization antenna can be regarded as two antennas with different polarization directions placed at the same spatial position. There is a certain spatial isolation between them, which can provide a certain spatial diversity gain. The dual circular polarization antenna can also process signals in two polarization directions simultaneously, reducing the number of antennas required in the communication system.

[0076] The embodiments of the present application have been described in detail above with reference to the accompanying drawings. However, the present application is not limited to the above embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art, various changes can be made without departing from the purpose of the present application. In addition, the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

Claims

1. A millimeter wave circularly polarized ridge gap waveguide antenna, characterized in that: The invention comprises a feeding waveguide layer, a waveguide slot layer, a grating lobe suppressor, a polarization converter and a radiation cavity layer which are stacked in sequence from bottom to top, wherein: The feeding waveguide layer comprises a first interdigital ridge and a central ridge, wherein the central ridge extends along the x-direction, the first interdigital ridges are divided into two groups and are symmetrically arranged on both sides of the central ridge, and the first interdigital ridges are arranged in an array along the x-direction; The waveguide slot layer is provided with second interdigital ridges, the second interdigital ridges are staggered with the first interdigital ridges and there are gaps between them, and the waveguide slot layer is provided with a plurality of first slots arranged along the x direction; The grating lobe suppressor is provided with a second gap capable of exposing the first gap; The polarization converter is provided with a plurality of cross-shaped slots which form an angle θ with the x direction, wherein θ is an acute angle or an obtuse angle; The radiation cavity layer is provided with a third gap capable of exposing the cross-shaped gap, and symmetrical steps are provided on both sides of the radiation cavity layer, and choke grooves are provided in the steps.

2. The millimeter wave circularly polarized ridge gap waveguide antenna according to claim 1, characterized in that: The gap width between the first interdigital ridges and the second interdigital ridges is one sixteenth of the wavelength of the center frequency.

3. The millimeter wave circularly polarized ridge gap waveguide antenna according to claim 1, characterized in that: The side surfaces of the central ridge are provided with non-uniformly arranged short ridges, and the middle portion of the central ridge is provided with a hollow feeding waveguide opening.

4. The millimeter wave circularly polarized ridge gap waveguide antenna according to claim 1, characterized in that: The first gaps are Taylor distributed or Chebyshev distributed along the x direction.

5. The millimeter wave circularly polarized ridge gap waveguide antenna according to claim 1, characterized in that: The cross-shaped gap consists of a wide gap and a narrow gap, and the wide gap and the narrow gap are perpendicular to each other.

6. The millimeter wave circularly polarized ridge gap waveguide antenna according to claim 5, characterized in that: The third slit is in a centrally symmetrical hexagonal shape, wherein the shorter side of the third slit corresponds to the narrow slit.

7. The millimeter wave circularly polarized ridge gap waveguide antenna according to claim 1, characterized in that: The depth of the choke slot is one quarter of the wavelength of the center frequency.

8. The millimeter wave circularly polarized ridge gap waveguide antenna according to any one of claims 1 to 7, characterized in that: The first interdigital ridges and the second interdigital ridges are both rectangular strip structures, and a row of the first interdigital ridges and a row of the second interdigital ridges are respectively arranged on both sides of the central ridge.

9. The millimeter wave circularly polarized ridge gap waveguide antenna according to any one of claims 1 to 7, characterized in that: The first interdigital ridges and the second interdigital ridges are both square structures, and three columns of the first interdigital ridges and three columns of the second interdigital ridges are respectively arranged on both sides of the central ridge.

10. The millimeter wave circularly polarized ridge gap waveguide antenna according to any one of claims 1 to 7, characterized in that: The first interdigital ridges and the second interdigital ridges are both cylindrical structures, and three rows of the first interdigital ridges and three rows of the second interdigital ridges are respectively arranged on both sides of the central ridge.

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