Millimeter wave radar antenna

Abstract

The utility model discloses a millimeter wave radar antenna, which relates to the technical field of antennas, and comprises a waveguide member, two opposite side surfaces of the waveguide member along a first direction are respectively an opening surface and an installation surface, the installation surface is used for installing a chip, and the opening surface is provided with a plurality of transmission holes penetrating through the installation surface. The transmission hole comprises a radiation section, a transmission section and a chip connection section; the radiation section is arranged close to the opening surface and is used for transmitting or receiving an electromagnetic signal transmitted through the free space towards the free space; the transmission section is connected with the radiation section and used for transmitting electromagnetic signals, and the transmission section comprises a bending section deviating from the radiation section; and the chip connecting section is connected with the bending section, extends along the first direction, is arranged close to the mounting surface, is adjacent to the mounting position of the chip, and is used for sending an electromagnetic signal to the chip or receiving the electromagnetic signal sent by the chip. According to the technical scheme of the utility model, flexible layout of the antenna can be realized so as to enhance the space utilization rate.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of antenna, especially relates to a millimeter wave radar antenna. BACKGROUND

[0002] The antenna form used by the automobile millimeter radar antenna includes PCB board antenna, and the PCB board antenna includes microstrip patch antenna, microstrip comb antenna and the like form, but under 30-300GHz base material, the antenna gain is small, the antenna efficiency is low, and the feeder loss is big.

[0003] Using waveguide antenna can improve antenna efficiency and reduce feeder loss, and common waveguide antennas include waveguide horn antenna, waveguide slot antenna and the like, but since the automobile millimeter wave radar antenna is usually MIMO array, requires that the antenna independent volume is small, the structure is compact, and the feeder wiring is flexible, and the volume of waveguide antenna is usually large, and the layout is not flexible.

[0004] Therefore, how to realize the flexible layout of the antenna becomes a problem to be solved by the person skilled in the art. UTILITY MODEL CONTENTS

[0005] The utility model discloses a millimeter wave radar antenna, which aims to realize the flexible layout of the antenna.

[0006] To achieve the above object, the millimeter wave radar antenna provided by the utility model includes a waveguide element, the opposite two sides of the waveguide element along a first direction are respectively an opening surface and a mounting surface, the mounting surface is used to mount a chip, the opening surface is provided with a plurality of transmission holes penetrating the mounting surface, the transmission hole includes a radiation section, a transmission section and a chip connecting section; the radiation section is arranged close to the opening surface and is used to emit or receive electromagnetic signals transmitted through the free space; the transmission section is connected with the radiation section and is used to transmit electromagnetic signals, the transmission section includes a bending section away from the radiation section, the bending section includes at least one first bending unit bent along a second direction, and / or, the bending section includes at least one second bending unit bent along a third direction; the chip connecting section is connected with the bending section, the chip connecting section extends along the first direction, is arranged close to the mounting surface and is adjacent to the mounting position of the chip, and is used to emit electromagnetic signals to the chip or receive electromagnetic signals emitted by the chip.

[0007] In an embodiment, the transmission section further includes a transition section and at least one opening connecting section; one end of the transition section is connected with the first bending unit and / or the second bending unit, and the cross-sectional area of the transition section is arranged to change along the transmission direction of the electromagnetic signals; one end of each opening connecting section is communicated with the transition section, and the other end is communicated with the radiation section.

[0008] In an embodiment, the transition section comprises a first matching section and a second matching section; the first matching section is connected with the first bending unit and / or the second bending unit, and the cross-sectional area of the first matching section gradually decreases in the direction from the chip connecting section to the radiation section; the two ends of the second matching section are connected with the first matching section and the opening connecting section respectively, and the second matching section comprises a main section and at least one branch section; the main section is connected with the first matching section, and the cross-sectional area of the main section is greater than the maximum cross-sectional area of the first matching section; the branch section is connected with the opening connecting section correspondingly.

[0009] In an embodiment, the inner side wall of the second matching section is provided with a protrusion, the height of the protrusion is a, and the wavelength of the electromagnetic signal is λ, a≤λ / 2.

[0010] In an embodiment, the waveguide further comprises at least one partition, and the at least one partition is arranged on the side wall of each radiation section to divide the radiation section into a plurality of radiation cavities arranged along the third direction, so as to enhance the concentration of the electromagnetic signal.

[0011] In an embodiment, the waveguide comprises a first waveguide plate and a second waveguide plate; one side of the first waveguide plate along the first direction forms an opening surface, and the other side of the first waveguide plate along the first direction is a first connecting surface; the opening surface is provided with a radiation slot, and the first connecting surface is provided with a first transmission slot communicated with the radiation slot; one side of the second waveguide plate along the first direction forms a mounting surface, and the other side of the second waveguide plate along the first direction is a second connecting surface; the second connecting surface is provided with a second transmission slot, and the bottom of the second transmission slot is provided with a transceiving slot; the second waveguide plate is stacked with the first waveguide plate, and the second connecting surface is attached with the first connecting surface, so that the first transmission slot and the second transmission slot are communicated; wherein the radiation slot forms a radiation section of a transmission hole, the first transmission slot and the second transmission slot jointly form a transmission section of the transmission hole, and the transceiving slot forms a chip connecting section of the transmission hole.

[0012] In an embodiment, the waveguide further comprises a conductive protrusion arranged at the mounting position of the chip, so as to reduce the leakage of the electromagnetic signal between the chip and the chip connecting section.

[0013] In an embodiment, the cross-sectional size of the chip connecting section gradually changes in the direction close to the transmission section.

[0014] In an embodiment, the waveguide is provided with an auxiliary slot on each side of each radiation section along the second direction, and the auxiliary slot extends along the third direction.

[0015] In an embodiment, the wavelength of the electromagnetic signal is λ, wherein the size of the auxiliary slot along the third direction is l, l=λ / 4; and / or the size of the auxiliary slot along the first direction is h, 1mm≤h≤1.5mm; and / or the distance between the center lines of the two auxiliary slots of each radiation section along the second direction is d, d=1.5λ.

[0016] In the technical solution of this utility model, the transmission path of the electromagnetic signal starts from the chip connection segment, passes through the transmission segment, and reaches the radiation segment. The first and second bending units of the radiation segment make the path of the transmission segment tortuous. Within the limited space of the millimeter-wave radar antenna, the length of the electromagnetic signal transmission path can be flexibly controlled, effectively improving signal transmission efficiency, reducing path loss, and ensuring stable antenna performance. Furthermore, the radiation segments of multiple transmission holes are integrated into the mounting position of the adjacent chip, making full use of the limited space of the millimeter-wave radar antenna to integrate the transmission holes and enhancing space utilization. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 A schematic diagram of the structure of an embodiment of the millimeter-wave radar antenna provided by this utility model;

[0019] Figure 2 for Figure 1 A schematic diagram of the back of a mid-millimeter wave radar antenna;

[0020] Figure 3 for Figure 1 A partial structural diagram of a mid-millimeter-wave radar antenna;

[0021] Figure 4 for Figure 3 Schematic diagram of the transmission hole in the diagram;

[0022] Figure 5 for Figure 4 A schematic diagram of the transition section structure in the middle;

[0023] Figure 6 for Figure 1 A schematic diagram of all transmission apertures of a mid-millimeter wave radar antenna;

[0024] Figure 7 A partial structural schematic diagram of another embodiment of the millimeter-wave radar antenna provided by this utility model;

[0025] Figure 8 for Figure 7 A schematic diagram of the transition section structure of the transmission hole;

[0026] Figure 9 for Figure 8 A top view of the transition section in the diagram;

[0027] Figure 10 To Figure 1 The directional diagram of the millimeter wave radar antenna.

[0028] Brief Description of the Drawings:

[0029] 100, millimeter wave radar antenna; 1, waveguide element; 1A, opening surface; 1B, mounting surface; 11, first waveguide plate; 12, second waveguide plate; 13, protrusion; 14, partition; 15, conductive protrusion; 2, transmission hole; 21, radiation section; 211, radiation cavity; 22, transmission section; 221, bending section; 222, transition section; 2221, first matching section; 2222, second matching section; 2222A, main section; 2222B, branch section; 223, opening connection section; 23, chip connection section; 3, auxiliary groove.

[0030] The implementation, functional features and advantages of the present application will be further described with reference to the accompanying drawings in conjunction with the embodiments. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0032] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative positional relationship, movement condition, etc. between the components in a certain posture, and if the certain posture changes, the directional indications also change accordingly.

[0033] In addition, if the embodiments of the present application involve descriptions of "first", "second", etc., the descriptions of "first", "second", etc. are only for description purposes, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first" and "second" can explicitly or implicitly include at least one of the features. In addition, "and / or" or "and / or" appearing throughout the text means that the three parallel schemes are included, for example, "A and / or B" includes A scheme, or B scheme, or A and B simultaneously satisfy the scheme. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the fact that a person skilled in the art can realize it, and when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, nor is it within the scope of protection required by the present application.

[0034] In the PCB antenna under the substrate of 30-300GHz, the antenna gain is small, the antenna efficiency is low, the feed line loss is large, and the volume of the waveguide antenna is usually large, and the layout is not flexible.

[0035] Based on this, the utility model provides a kind of millimeter wave radar antenna 100.

[0036] Please refer to Figure 1 With Figure 4 In an embodiment of the utility model, the millimeter wave radar antenna 100 includes waveguide 1, and the opposite two sides of waveguide 1 along the first direction are respectively opening face 1A and mounting surface 1B, and mounting surface 1B is used to install chip, and opening face 1A is provided with multiple transmission holes 2 penetrating mounting surface 1B, and transmission hole 2 includes radiation section 21, transmission section 22 and chip connecting section 23;Radiation section 21 is close to opening face 1A and is used to emit or receive electromagnetic signal transmitted by free space to free space;Transmission section 22 is connected with radiation section 21, and is used to transmit electromagnetic signal, and transmission section 22 includes bending section 221 away from radiation section 21, and bending section 221 includes at least one first bending unit bending along the second direction, and / or, bending section 221 includes at least one second bending unit bending along the third direction;Chip connecting section 23 is connected with bending section 221, and chip connecting section 23 extends along the first direction, is close to mounting surface 1B and is set to the installation position adjacent to chip, and is used to emit electromagnetic signal to chip or receive electromagnetic signal emitted by chip.

[0037] In the technical scheme of the utility model, the transmission path of electromagnetic signal starts from chip connecting section 23, reaches radiation section 21 after transmission section 22, and the first bending unit and the second bending unit of radiation section 21 make the path of transmission section 22 winding, flexibly control the length of transmission path of electromagnetic signal in the limited space of millimeter wave radar antenna 100, effectively improve signal transmission efficiency, reduce path loss, ensure that antenna performance is stable, and the radiation section 21 of multiple transmission holes 2 is integrated in the installation position adjacent to chip, fully utilizes the limited space of millimeter wave radar antenna 100 to integrate transmission hole 2, and the space utilization is enhanced.

[0038] It should be noted that, in multiple transmission holes 2, part of transmission hole 2 is used as receiving antenna, and the rest of transmission hole 2 is used as transmitting antenna, and through reasonable layout and design, the optimization configuration of receiving and transmitting function can be realized, and the overall performance of antenna is improved, and in some embodiments, waveguide 1 is provided with eight transmission holes 2, four of which are used for receiving signal, and four of which are used for transmitting signal, and eight transmission holes 2 are distributed in MIMO array.

[0039] And the length of the plurality of transmission holes 2 is controlled via the bending design of the transmission section 22, so that the electromagnetic signals emitted by each transmission hole 2 are in phase.

[0040] The second direction and the third direction are two mutually perpendicular directions perpendicular to the first direction, and the transmission section 22 is bent at least in one of the second direction or the third direction.

[0041] Please refer to Figure 6 In an embodiment, the transmission section 22 includes a first bending unit bent in the second direction and a second bending unit bent in the third direction, and has an "L" shape or an approximate "L" shape; in another embodiment, the transmission section 22 includes a plurality of first bending units bent in the second direction and a plurality of second bending units bent in the third direction, and has an "S" shape or an approximate "S" shape, or a "U" shape or an approximate "U" shape.

[0042] In an embodiment of the utility model, the transmission section 22 further includes a transition section 222 and at least one opening connecting section 223; one end of the transition section 222 is connected with the first bending unit and / or the second bending unit, and the cross-sectional area of the transition section 222 is arranged to change in the direction of transmission of the electromagnetic signals; one end of each opening connecting section 223 is in communication with the transition section 222, and the other end is in communication with the radiation section 21. In this way, the bandwidth matching of the millimeter wave radar antenna 100 is realized.

[0043] Please refer to Figure 5 In an embodiment of the utility model, the transition section 222 includes a first matching section 2221 and a second matching section 2222; the first matching section 2221 is connected with the first bending unit and / or the second bending unit, and the cross-sectional area of the first matching section 2221 is arranged to gradually decrease in the direction from the chip connecting section 23 to the radiation section 21; the two ends of the second matching section 2222 are in communication with the first matching section 2221 and the opening connecting section 223 respectively, and the second matching section 2222 includes a main section 2222A and at least one branch section 2222B; the main section 2222A is connected with the first matching section 2221, and the cross-sectional area of the main section 2222A is greater than the maximum cross-sectional area of the first matching section 2221; the branch section 2222B is connected with the opening connecting section 223 correspondingly. In this way, the stability and efficiency in the signal transmission process are ensured through the step-by-step matching optimization. Specifically, the cross-sectional area of each branch section 2222B is smaller than that of the main section 2222A, forming a gradient change, so that the electromagnetic signals can be smoothly transitioned during transmission, reducing reflection and loss, and thus improving the performance of the antenna.

[0044] In an embodiment of the utility model, the inner side wall of the second matching section 2222 is provided with a protrusion 13, the height of the protrusion 13 is a, the wavelength of the electromagnetic signal is λ, a≤λ / 2. In this way, the protrusion 13 plays a role in improving the electromagnetic signal propagation characteristics. By providing the protrusion 13 on the inner side wall, the scattering of the electromagnetic signal during transmission can be increased, thereby enhancing the uniformity of the signal in different directions, and since the height of the protrusion 13 is controlled to be less than half of the wavelength, this ensures that the electromagnetic signal will not cause serious interference effects when passing through the protrusion 13, but will be guided and dispersed in a relatively smooth manner.

[0045] It should be noted that the number of protrusions 13 is related to the number of branch sections 2222B, and a plurality of protrusions 13 are respectively arranged at the interval positions between each adjacent two branch sections 2222B and the connection between the main body section 2222A.

[0046] Please refer to Figures 7 to 9 In an embodiment of the utility model, the waveguide 1 further comprises at least one partition 14, and the at least one partition 14 is arranged on the side wall of each radiation section 21 to separate the radiation section 21 into a plurality of radiation cavities 211 arranged along a third direction, thereby enhancing the concentration of the electromagnetic signal. In this way, the arrangement of the plurality of radiation cavities 211 enables the electromagnetic signal to be better directionally propagated in space, thereby improving the radiation efficiency and directivity of the antenna.

[0047] In one embodiment, the physical structure of the partition 14 is formed when the transmission hole 2 is opened; in another embodiment, the partition 14 is designed by embedding and closely adheres to the side wall of the radiation section 21.

[0048] It should be noted that the number of radiation cavities 211 has no fixed corresponding relationship with the number of protrusions 13, and can be flexibly adjusted according to specific design and performance requirements. In some embodiments, the number of radiation cavities 211 is large to cover a wider propagation angle, and in other embodiments, the reduction in the number of radiation cavities 211 helps to enhance the transmission intensity of the signal in a specific direction.

[0049] Furthermore, the number of protrusions 13 arranged on the inner side wall of the second matching section 2222, the number of branch sections 2222B, the number of opening connection sections 223, and the number of radiation cavities 211 are matched to achieve the best signal distribution and propagation effect, and the propagation path of the electromagnetic signal in each transmission hole 2 is the chip connection section 23-bending section 221-first matching section 2221-second matching section 2222-main body section 2222A of the second matching section 2222-a plurality of branch sections 2222B-a plurality of opening connection sections 223-a plurality of radiation cavities 211, wherein a plurality of branch sections 2222B and a plurality of opening connection sections 223 are correspondingly arranged, each opening connection section 223 is connected to at least one radiation cavity 211.

[0050] In an embodiment of the present application, the waveguide 1 comprises a first waveguide plate 11 and a second waveguide plate 12; the first waveguide plate 11 forms an opening surface 1A on one side along a first direction, and forms a first connecting surface on the other side along the first direction; the opening surface 1A is provided with a radiation slot, and the first connecting surface is provided with a first transmission slot in communication with the radiation slot; the second waveguide plate 12 forms a mounting surface 1B on one side along the first direction, and forms a second connecting surface on the other side along the first direction; the second connecting surface is provided with a second transmission slot, and the bottom of the second transmission slot is provided with a transceiving slot; the second waveguide plate 12 is stacked with the first waveguide plate 11, and the second connecting surface is attached to the first connecting surface, so that the first transmission slot and the second transmission slot are in communication; wherein the radiation slot forms a radiation section 21 of a transmission hole 2, the first transmission slot and the second transmission slot jointly form a transmission section 22 of the transmission hole 2, and the transceiving slot forms a chip connecting section 23 of the transmission hole 2. In this way, the first waveguide plate 11 and the second waveguide plate 12 can be independently processed and assembled into a complete waveguide 1, greatly reducing the production cost and simplifying the assembly process.

[0051] Referring to Figure 2 In an embodiment of the present application, the waveguide 1 further comprises a conductive protrusion 15, which is arranged at the mounting position of the chip to reduce the leakage of electromagnetic signals between the chip and the chip connecting section 23. In this way, the conductive protrusion 15 provides additional protection for the transmission of electromagnetic signals, which helps to reduce the loss of electromagnetic signals and improve the stability and reliability of electromagnetic signals.

[0052] In an embodiment, the conductive protrusion 15 comprises a plurality of metal columns arranged on the mounting surface 1B, and the metal columns are fixed on the mounting surface 1B by welding or crimping. The arrangement of the metal columns can also provide structural support to ensure the stability of the chip under high-frequency working conditions and prevent micro-displacement caused by vibration or temperature changes.

[0053] In an embodiment of the present application, the cross-sectional size of the chip connecting section 23 gradually changes in the direction close to the transmission section 22. In this way, a progressive impedance matching is formed, thereby reducing reflection and loss.

[0054] Referring to Figure 3 In an embodiment of the present application, the waveguide 1 is provided with an auxiliary slot 3 on both sides of each radiation section 21 along a second direction, and the auxiliary slot 3 extends along a third direction. In this way, by arranging the auxiliary slot 3, the radiation section 21 forms a wide beam pattern as shown in Figure 10 The auxiliary slot 3 can optimize the radiation characteristics, so that the waveguide 1 can maintain good radiation effect at different angles.

[0055] In an embodiment of the utility model, the wavelength of electromagnetic signal is λ, wherein the size of auxiliary groove 3 along the third direction is l, l = λ / 4. The length of the radiation groove is set to one fourth of the wavelength λ, which can realize further matching of impedance, reduce the reflection of electromagnetic wave in waveguide 1, and ensure that the signal can be transmitted more efficiently.

[0056] In an embodiment of the utility model, the size of auxiliary groove 3 along the first direction is h, 1mm ≤ h ≤ 1.5mm. Adjusting the depth of the radiation groove can effectively control the radiation range and direction of electromagnetic wave, and improve the overall performance of waveguide 1.

[0057] In an embodiment of the utility model, the distance between the center lines of the two auxiliary grooves 3 of each radiation section 21 along the second direction is d, d = 1.5λ. This can further optimize the directional diagram of waveguide 1, enhance the consistency of beam width, and thus provide more uniform radiation effect in different application environments.

[0058] The above is only an exemplary embodiment of the utility model, and does not limit the patent range of the utility model, and any equivalent structural transformation made by using the utility model specification and drawings, or direct / indirect application in other related technical fields is included in the patent protection range of the utility model.

Claims

1. A millimeter-wave radar antenna, characterized in that, The waveguide includes an opening surface and a mounting surface on two opposite sides along a first direction. The mounting surface is used to mount a chip. The opening surface has a plurality of transmission holes penetrating the mounting surface. The transmission holes include: The radiating section is positioned close to the opening surface to emit or receive electromagnetic signals transmitted through free space. A transmission segment, connected to the radiation segment, for transmitting electromagnetic signals, the transmission segment including a bent segment away from the radiation segment, the bent segment including at least one first bent element bent along a second direction, and / or, the bent segment including at least one second bent element bent along a third direction; and, A chip connection segment is connected to the bent segment. The chip connection segment extends along a first direction, is disposed close to the mounting surface, and is adjacent to the mounting position of the chip, for emitting electromagnetic signals toward or receiving electromagnetic signals emitted by the chip.

2. The millimeter-wave radar antenna as described in claim 1, characterized in that, The transmission segment also includes: A transition section, one end of which is connected to the first bending unit and / or the second bending unit, has a varying cross-sectional area along the transmission direction of the electromagnetic signal; and... At least one open connecting segment, one end of each open connecting segment being connected to the transition segment and the other end being connected to the radiation segment.

3. The millimeter-wave radar antenna as described in claim 2, characterized in that, The transition section includes: A first matching segment, connected to the first bending unit and / or the second bending unit, has a cross-sectional area that gradually decreases along the direction from the chip connection segment to the radiation segment; and, The second matching segment is connected to the first matching segment and the opening connection segment at both ends. The second matching segment includes a main segment and at least one branch segment. The main segment is connected to the first matching segment, and the cross-sectional area of ​​the main segment is greater than the maximum cross-sectional area of ​​the first matching segment. The branch segment is correspondingly connected to the opening connection segment.

4. The millimeter-wave radar antenna as described in claim 3, characterized in that, The inner wall of the second matching segment is provided with a protrusion, the height of the protrusion is a, the wavelength of the electromagnetic signal is λ, and a≤λ / 4.

5. The millimeter-wave radar antenna as described in claim 2, characterized in that, The waveguide further includes at least one separator, which is disposed on the sidewall of each of the radiation segments to form multiple radiation cavities arranged along a third direction, thereby enhancing the concentration of the electromagnetic signal.

6. The millimeter-wave radar antenna as described in claim 1, characterized in that, The waveguide includes: A first waveguide plate has an opening surface formed on one side along a first direction, and a first connecting surface on the other side along the first direction. A radiation groove is formed on the opening surface, and a first transmission groove communicating with the radiation groove is formed on the first connecting surface. The second waveguide plate has a mounting surface formed on one side along the first direction and a second connecting surface on the other side along the first direction. A second transmission groove is formed on the second connecting surface, and a transceiver groove is formed at the bottom of the second transmission groove. The second waveguide plate is stacked with the first waveguide plate, and the second connecting surface is attached to the first connecting surface so that the first transmission groove and the second transmission groove are connected. The radiation slot forms the radiation section of the transmission hole, the first transmission slot and the second transmission slot together form the transmission section of the transmission hole, and the transceiver slot forms the chip connection section of the transmission hole.

7. The millimeter-wave radar antenna as described in claim 1, characterized in that, The waveguide also includes conductive protrusions disposed at the mounting position of the chip to reduce electromagnetic signal leakage between the chip and the chip connection segment.

8. The millimeter-wave radar antenna as described in claim 1, characterized in that, Along the direction close to the transmission segment, the cross-sectional dimensions of the chip connection segment are gradually varied.

9. The millimeter-wave radar antenna as described in claim 1, characterized in that, The waveguide has auxiliary grooves on both sides of each of the radiation segments along the second direction, and the auxiliary grooves extend along the third direction.

10. The millimeter-wave radar antenna as described in claim 9, characterized in that, The wavelength of the electromagnetic signal is λ, where, The auxiliary groove has a dimension l along the third direction, where l = λ / 4; and / or, The dimension of the auxiliary groove along the first direction is h, where 1mm ≤ h ≤ 1.5mm; and / or, The distance between the centerlines of the two auxiliary slots of each radiation section along the second direction is d, where d = 1.5λ.

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