Broadband fixed-beam leaky-wave antenna with filtering characteristic

Abstract

The invention belongs to the field of millimeter wave point-to-point communication, and particularly relates to a broadband fixed-beam leaky-wave antenna with a filtering characteristic. The substrate integrated coaxial line transmission structure is adopted to feed the two ends of the leaky-wave structure, and the substrate integrated coaxial line transmits quasi-TEM waves and has a very weak dispersion characteristic, and the phase constant beta of the quasi-TEM waves changes slightly in a wide frequency band range, so that a fixed radiation wave beam can be obtained in a certain frequency band range; inversion signals are fed at the two ends of the leaky-wave structure so that the two wave beams can form a main wave beam, when the two wave beams deviate from the broadside to radiate by a certain angle, a wave beam with good radiation can still be formed, and therefore the bandwidth corresponding to the fixed radiation wave beam is further widened. On the basis, a plurality of radiation matching units are sequentially arranged on the metal strip in the length direction of the metal strip, so that the fixed-beam leaky-wave antenna has the characteristics that the angle of a radiation beam is kept unchanged in a relatively wide bandwidth, the gain is high, the efficiency is high and the side lobe is low.

Description

Technical Field

[0001] The invention belongs to the field of millimeter wave point-to-point communication, and in particular relates to a broadband fixed-beam leaky-wave antenna with filtering characteristics. Background Art

[0002] Leaky wave antennas (LWAs) are defined as traveling wave antennas with varying radiation patterns at different frequencies. They have a simple feeding structure and can easily obtain narrow beams by controlling the leakage wave rate and antenna length. Compared with phased array antennas, they have the advantages of low cost, simple geometry, and wide bandwidth. In fact, the frequency-dependent beam scanning characteristics of leaky wave antennas can be understood as the inherent basic properties of modal dispersion. In naturally occurring dispersive media, dispersion constraints can be expressed by the Kramer-Kroning relation and the Bode relation, which are frequency-dependent real and imaginary linear response functions.

[0003] The frequency-dependent beam scanning characteristics of leaky wave antennas have been studied and utilized to realize real-time spectrum analyzers and radar sensors. However, for point-to-point communication and high-capacity broadband communication, the frequency-dependent beam scanning characteristics are not desirable.

[0004] Some work has been done to reduce the angle of the beam as the frequency is scanned by alleviating the angular dispersion effect: low-dispersion fast waves are generated in the waveguide structure, a multi-layer gold cover is used, and a gas-filled hollow waveguide is formed using bulk silicon microelectromechanical system micromachining (MEMS) technology. By creating a leaky slot on its upper surface, a slowly varying dispersion curve is achieved within the fixed beam radiation range of 55 to 67 GHz; there are also reports on an air-filled substrate integrated waveguide leaky wave antenna, which achieves a fixed beam of 60°±2° within a fractional bandwidth of 28.6% by optimizing the flattening of the dispersion curve through appropriate parameters. There are also works that use dispersion compensation mechanisms to achieve a broadband directional beam leaky lens antenna. However, in the design, the dielectric lens integrated in the long slot leaky wave antenna is very bulky and requires the use of an all-metal structure and / or requires complex manufacturing / assembly processes. They may not be suitable for planar system integration with other active / passive components, nor for mass production using standard / mature low-cost PCB processes.

[0005] An effective method to fix the radiation beam is the quasi-TEM mode fixed-beam leaky-wave antenna. Since the ratio between the propagation constant β and the free-space wave number k is almost constant, the radiation angle can be limited to a small area in the front quadrant or end-fire.

[0006] A Chinese patent with publication number CN110581363A discloses a fixed-beam leaky-wave antenna with customizable output angle. The leaky-wave antenna includes a gap ridge waveguide, a triangular metal prism and a transmission-type phase gradient surface structure. The leaky-wave antenna reduces the characteristic of the existing leaky-wave antenna that the radiation beam scans rapidly with frequency, fixes the radiation beam within a small angle range within a large bandwidth, and can customize the required fixed beam angle range according to requirements. The advantage is high flexibility, and the disadvantage is large size, expensive and complex processing, and complex assembly.

[0007] The Chinese patent with publication number CN113316868A discloses a double-end-fed broadside leaky wave antenna, in which the opposite ends of the leaky wave structure are fed with an inverted version of a common signal, resulting in the broadside frequency being separated from the open stopband. To achieve this, the common signal can be divided into two equal-length paths, one including a perfect electric conductor (PEC) reflector and the other including a perfect magnetic conductor (PMC) reflector. In addition, the common signal can be divided into two paths that differ by half a wavelength in length. A power divider and a feed horn can be used in the corresponding paths. The leaky wave structure can have a transverse groove, the width of which increases toward the midpoint of the structure. It can be formed on a single planar portion of a photolithographic structure, for example by patterning a conductive layer thereon. However, the antenna only achieves broadside fixed beam radiation at 27.5GHz-28GHz and does not have out-of-band filtering characteristics.

[0008] It can be seen that the fixed-beam leaky-wave antenna in the prior art usually uses an all-metal structure, has a complex manufacturing or assembly process, and is large in size; while the quasi-TEM mode fixed-beam leaky-wave antenna still has a beam outside the working frequency band corresponding to the fixed radiation beam, which affects its application in the field of millimeter-wave point-to-point communications when used as a receiving antenna. Summary of the invention

[0009] The purpose of the present invention is to provide a broadband fixed-beam leaky-wave antenna with filtering characteristics. The antenna is a full-planar quasi-TEM mode leaky-wave antenna with broadband fixed-beam radiation and out-of-band filtering characteristics. It has the advantages of simple process, low cost, small size, high gain, high efficiency, low side lobe, etc., and is suitable for millimeter-wave point-to-point communication.

[0010] To achieve the above object, the present invention adopts the following technical solution:

[0011] A fixed-beam leaky-wave antenna with out-of-band filtering characteristics comprises: a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer, a third metal layer, a third dielectric layer, a fourth metal layer and a metal feed layer, which are stacked in sequence from top to bottom;

[0012] The first metal layer is composed of a plurality of pairs of radiation patches;

[0013] The first dielectric layer is provided with a plurality of pairs of first metallized through holes,

[0014] The second metal layer is provided with a plurality of radiation slots;

[0015] The second dielectric layer is provided with a plurality of second metallized through holes, and the plurality of second metallized through holes are arranged in a rectangular shape;

[0016] The third metal layer is provided with three through-matching grooves, the three matching grooves include two first matching grooves and one second matching groove; the second matching groove is provided between the two first matching grooves, and a metal strip is provided on the line connecting the midpoints of the two wide sides thereof;

[0017] The third dielectric layer has the same structure as the second dielectric layer 4;

[0018] A coupling window is provided at each end of the fourth metal layer, each coupling window is provided with a coupling patch whose size is smaller than the coupling window, and one end of the coupling patch is connected to the fourth metal layer;

[0019] A differential feeding transition structure, a first band-pass filter and a second band-pass filter are provided on the metal feeding layer, the input of the differential feeding structure is connected to the external excitation structure, and the output is connected to the first band-pass filter and the second band-pass filter respectively;

[0020] A plurality of pairs of radiation patches, a plurality of radiation slots, a plurality of pairs of first metallized through holes and a plurality of matching units are arranged correspondingly in the vertical direction, two coupling windows and two first rectangular slots are arranged correspondingly in the vertical direction, the first metal layer, the first dielectric layer and the second metal layer together constitute a leaky wave structure; the second metal layer, the second dielectric layer, the third metal layer and the third dielectric layer, the metal strip and the second metallized through hole together constitute a substrate-integrated coaxial line transmission structure.

[0021] Furthermore, the spacing between the second metallized through holes located on the two long sides and close to the wide sides at both ends of the rectangle in which the multiple second metallized through holes are arranged is reduced to divide the space surrounded by the second metallized through holes into five parts, which are the first area, the second area, the third area, the fourth area and the fifth area, respectively, wherein the first area and the fifth area are located at both ends.

[0022] Furthermore, the first area and the fifth rectangular area correspond to two coupling slots in the vertical direction respectively.

[0023] Furthermore, the matching grooves provided on the third metal layer are all rectangular grooves.

[0024] Furthermore, a plurality of radiation matching units are sequentially arranged on the metal strip along its length direction, and each radiation matching unit is composed of a metal patch.

[0025] Furthermore, the first radiation matching unit and the last radiation matching unit among the multiple radiation matching units are composed of two first metal patches, and the two metal patches are symmetrically arranged on both sides of the metal strip; the multiple radiation matching units between the first radiation matching unit and the last radiation matching unit are each composed of four first metal patches, each two first metal patches constitute a group, and the two groups of first metal patches are symmetrically arranged on both sides of the metal strip.

[0026] Furthermore, each pair of radiation patches is composed of two symmetrical rectangular metal patches, and the two coupling windows are both trapezoidal coupling windows.

[0027] Furthermore, the metal feeding layer is provided with a fourth rectangular groove, and two wide sides of the fourth rectangular groove are chamfered to form a trapezoidal structure similar to the coupling window.

[0028] Furthermore, the differential transition structure is manufactured by CNC processing technology, and the substrate-integrated coaxial line transmission structure and the leaky wave structure are both manufactured by PCB substrate processing technology.

[0029] Furthermore, the radiation slot is a bowtie-shaped slot.

[0030] Furthermore, a third metallized through hole is provided in the middle position of the first area and the fifth area, and two pairs of fourth metallized through holes are provided at both ends of the third area respectively, and the connection line of the centers of the two pairs of fourth metallized through holes is parallel to the connection line of the centers of the second metallized through holes forming the second area or the fourth area.

[0031] Due to the adoption of the above technical solution, the present invention has the following advantages:

[0032] 1. The fixed-beam leaky-wave antenna of the present invention is provided with a first bandpass filter and a second bandpass filter in a metal feeding layer; one end of the first bandpass filter is connected to the first output end of the differential transition structure, and the other end is connected to the substrate-integrated coaxial line transmission structure through a coupling window at one end of the fourth metal layer; one end of the second bandpass filter is connected to the second output end of the differential transition structure, and the other end of the fourth metal layer is connected to the substrate-integrated coaxial line transmission structure through a coupling window at one end, that is, two bandpass filters are integrated in the path of the feeding signal, and out-of-band filtering characteristics are achieved without increasing the volume of the antenna, thereby suppressing the radiation beam outside the working frequency band corresponding to the fixed radiation beam, so that it can be better used in millimeter-wave point-to-point communication.

[0033] 2. The present invention uses a substrate integrated coaxial line transmission structure to feed the leaky wave structure at both ends, and the signal fed at both ends is an inverted signal. Since the substrate integrated coaxial line transmits a quasi-TEM wave, it has a very weak dispersion characteristic, and its phase constant β changes little within a wider frequency band, so a fixed radiation beam can be obtained within a certain frequency band. Feeding an inverted signal at both ends of the leaky wave structure allows the two beams to be synthesized into a main beam. When the two beams deviate from the wide side radiation by a certain angle, they can still be synthesized into a beam with better radiation, thereby further widening the bandwidth corresponding to the fixed radiation beam. On this basis, by sequentially arranging a plurality of radiation matching units on the metal strip along its length direction, the fixed beam leaky wave antenna of the present invention has the characteristics of keeping the angle of the radiation beam unchanged within a wider bandwidth, high gain, high efficiency, and low side lobe.

[0034] 3. The differential transition structure and bandpass filter structure connecting the fixed-beam leaky-wave antenna and the standard waveguide are processed by CNC technology, and the substrate-integrated coaxial line and the leaky-wave structure are processed by PCB substrate technology. They are assembled by screws and holes reserved on metal parts and substrate parts, which has low cost and simple assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the overall structure of a fixed-beam leaky-wave antenna with out-of-band filtering characteristics according to an embodiment;

[0036] Figure 2 A layered model diagram of a fixed-beam leaky-wave antenna with out-of-band filtering characteristics in an embodiment;

[0037] Figure 3 It is a schematic diagram of the structure of a leaky wave unit of a fixed-beam leaky wave antenna with out-of-band filtering characteristics in an embodiment;

[0038] Figure 4 It is a schematic diagram of the differential feeding transition structure to substrate integrated coaxial line transmission structure of the fixed beam leaky wave antenna with out-of-band filtering characteristics in the embodiment;

[0039] Figure 5 is a simulated reflection coefficient of a fixed-beam leaky-wave antenna having out-of-band filtering characteristics of an embodiment;

[0040] Figure 6 is the actual gain of the fixed-beam leaky-wave antenna with out-of-band filtering characteristics of the embodiment;

[0041] Figure 7 The simulated radiation efficiency of the fixed-beam leaky-wave antenna with out-of-band filtering characteristics of the embodiment;

[0042] Figure 8 The fixed beam leaky wave antenna with out-of-band filtering characteristics at 26.8 GHz is shown in FIG. Z Normalized simulated radiation pattern at ;

[0043] Fig. 9 The fixed beam leaky wave antenna with out-of-band filtering characteristics at 27 GHz is shown in the following example. Z Normalized simulated radiation pattern at ;

[0044] Fig.10 The fixed beam leaky wave antenna with out-of-band filtering characteristics at 27.7 GHz is shown in FIG. Z Normalized simulated radiation pattern at ;

[0045] Fig.11 The fixed beam leaky wave antenna with out-of-band filtering characteristics at 28 GHz is shown in FIG. Z Normalized simulated radiation pattern at ;

[0046] Fig.12 The fixed beam leaky wave antenna with out-of-band filtering characteristics at 28.3 GHz is shown in FIG. Z Normalized simulated radiation pattern at ;

[0047] Fig.13 The fixed beam leaky wave antenna with out-of-band filtering characteristics at 28.6 GHz is shown in FIG. Z Normalized simulated radiation pattern at ;

[0048] Fig.14 The fixed beam leaky wave antenna with out-of-band filtering characteristics at 29.2 GHz is shown in FIG. Z Normalized simulated radiation pattern at ;

[0049] Fig.15 A signal transmission path of a fixed-beam leaky-wave antenna having out-of-band filtering characteristics in an embodiment;

[0050] Reference numerals:

[0051] 1 is the first metal layer, 2 is the first dielectric layer, 3 is the second metal layer, 4 is the second dielectric layer, 5 is the third metal layer, 6 is the third dielectric layer, 7 is the fourth metal layer, 8 is the differential transition structure, 9 is the bandpass filter, 10 is the rectangular radiation patch, 11 is the first metallized through hole, 12 is the radiation slot, 13 is the metal strip, 14 is the outer conductor of the substrate coaxial line, 15 is the first matching short-circuit column, 16 is the second matching short-circuit column (third metallized through hole), and 17 is the coupling patch. DETAILED DESCRIPTION

[0052] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

[0053] like Figure 1-Figure 4As shown, the present embodiment provides a fixed-beam leaky-wave antenna with out-of-band filtering characteristics, comprising a first metal layer 1, a first dielectric layer 2, a second metal layer 3, a second dielectric layer 4, a third metal layer 5, a third dielectric layer 6, a fourth metal layer 7 and a metal feed layer stacked in sequence from top to bottom.

[0054] The first metal layer 1 is composed of a plurality of pairs of radiation patches, each pair of radiation patches is composed of two symmetrical rectangular metal patches. The two coupling windows are trapezoidal coupling windows.

[0055] The first dielectric layer 2 is provided with a plurality of pairs of first metallized through holes 11 .

[0056] The second metal layer 3 is provided with a plurality of radiation slots 12, which serve as radiation structures on one hand and are used to couple the energy transmitted on the substrate integrated coaxial line to the radiation patch on the other hand to increase the radiation coupling amount. In this embodiment, the radiation slots 12 are configured as bowtie-shaped slots.

[0057] The second dielectric layer 4 is provided with a plurality of second metallized through holes, and the plurality of second metallized through holes are arranged in a rectangle. The x direction is defined as the long side of the rectangle, and the y direction is defined as the wide side of the rectangle. The spacing between the second metallized through holes at both ends of the rectangle where the plurality of second metallized through holes are arranged, which are located on the two long sides and close to the wide sides, is reduced to divide the space surrounded by the second metallized through holes into five parts, which are the first area, the second area, the third area, the fourth area and the fifth area in sequence. A third metallized through hole is provided in the middle of the first area and the fifth area, and two pairs of fourth metallized through holes are provided at both ends of the third area, respectively, and the connection line of the centers of the two pairs of fourth metallized through holes is parallel to the connection line of the centers of the second metallized through holes forming the second area or the fourth area.

[0058] The third metal layer 5 is provided with three through rectangular grooves, including two first rectangular grooves and one second rectangular groove; the second rectangular groove is provided between the two first rectangular grooves, and a metal strip is provided on the midpoint line of the two wide sides thereof, and a plurality of radiation matching units are provided on the metal strip in sequence along the length direction thereof. The radiation matching unit is composed of metal patches. The first radiation matching unit and the last radiation matching unit among the plurality of radiation matching units are composed of two first metal patches, and the two metal patches are symmetrically arranged on both sides of the metal strip; the plurality of radiation matching units between the first radiation matching unit and the last radiation matching unit are each composed of four first metal patches, and each two first metal patches constitute a group, and the two groups of first metal patches are symmetrically arranged on both sides of the metal strip.

[0059] The third dielectric layer 6 has the same structure as the second dielectric layer 4 .

[0060] A coupling window is disposed at each end of the fourth metal layer 7 . Each coupling window is provided with a coupling patch 17 smaller than the coupling window. One end of the coupling patch 17 is connected to the fourth metal layer 7 .

[0061] Among them, multiple pairs of radiation patches, multiple radiation slots, multiple pairs of first metallized through holes and multiple matching units are arranged in a corresponding manner in the vertical direction, wherein the first area and the fifth area on the second dielectric layer 4 and the third dielectric layer 6, and the two coupling windows on the fourth metal layer 7 are arranged in a corresponding manner in the vertical direction with the two first rectangular slots on the third metal layer 5. The first metal layer 1, the first dielectric layer 2, the second metal layer 3, and together constitute a leaky wave structure. The second metal layer 3, the second dielectric layer 4, the third metal layer 5 and the third dielectric layer 6, the metal strip 13 and the second metallized through hole together constitute a substrate integrated coaxial line transmission structure, in which the metal strip 13 is used as an inner conductor. The metal wall of the second metallized through hole on the second dielectric layer 4 and the third dielectric layer 6 forms the outer conductor 14 of the substrate integrated coaxial line. The metal wall of the fourth metallized through hole forms a first matching short-circuit column 15, and the first matching short-circuit column is used to improve the matching performance when the width of the inner conductor of the substrate integrated coaxial line remains unchanged and the outer conductor gradually widens. The metal wall of the third metallized through-hole forms a second matching short-circuit column 16, which connects the inner conductor of the substrate-integrated coaxial line and the coupling patch 17, and forms a monopole antenna mode with the coupling patch 17, thereby converting the TE wave transmitted by the substrate-integrated waveguide into the TEM wave transmitted by the substrate-integrated coaxial line, thereby achieving simultaneous matching of mode and impedance.

[0062] The metal feed layer is provided with a fourth rectangular slot, a differential feed transition structure, a first bandpass filter and a second bandpass filter. The two wide chamfers of the fourth rectangular slot are in a trapezoidal structure similar to the coupling window, so that the TE wave transmitted by the substrate integrated waveguide is better converted into the TEM wave transmitted by the substrate integrated coaxial line, so that more energy is transferred from the metal feed layer to the substrate integrated coaxial line. The differential feed transition structure, the first bandpass filter and the second bandpass filter are located in the fourth rectangular slot. The input of the differential feed structure is connected to the external excitation structure, and the output is connected to the first bandpass filter and the second bandpass filter respectively.

[0063] During implementation, the differential transition structure and the bandpass filter structure are prepared by CNC processing technology, the substrate integrated coaxial line and the leaky wave structure are prepared by PCB substrate processing technology, and they are assembled by screws and holes reserved on metal parts and substrate parts, which has low cost and simple assembly.

[0064] Figure 5 is the simulated reflection coefficient of the fixed-beam leaky-wave antenna with out-of-band filtering characteristics of the embodiment, through Figure 5 It can be seen that the reflection coefficients within the working frequency band are all lower than -10dB, indicating that most of the energy can be radiated into space.

[0065] Figure 6 The actual gain of the fixed-beam leaky-wave antenna with out-of-band filtering characteristics in the embodiment is greater than 15 dBi within the working frequency band, which has a relatively high gain.

[0066] Figure 7 : is the simulated radiation efficiency of the fixed-beam leaky-wave antenna with out-of-band filtering characteristics in the embodiment. The radiation efficiency of the antenna in the working frequency band is greater than 90%, indicating that the antenna in the embodiment has a very high efficiency.

[0067] Figure 8-Figure 14 The normalized simulated radiation patterns of the fixed-beam leaky-wave antenna with out-of-band filtering characteristics at 7 different frequencies are shown in the embodiment. Figure 8-Figure 14 The main lobes of the radiation patterns shown are all normal, indicating that the antenna has good fixed radiation beam characteristics.

[0068] Fig.15 The signal direction of the fixed-beam leaky-wave antenna with out-of-band filtering characteristics is shown in the black arrow. The signal is fed from the metal feeding layer and fed from the middle of the leaky-wave antenna to both ends. The two signals are of equal amplitude and inverse phase, and are transmitted to the substrate integrated coaxial line through the coupling window, and finally radiated into space through the radiation slot and the radiation patch.

[0069] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. A fixed-beam leaky-wave antenna with out-of-band filtering characteristics, comprising: a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer, a third metal layer, a third dielectric layer, a fourth metal layer and a metal feed layer stacked in sequence from top to bottom, characterized in that: The first metal layer is composed of a plurality of pairs of radiation patches; The first dielectric layer is provided with a plurality of pairs of first metallized through holes, The second metal layer is provided with a plurality of radiation slots; The second dielectric layer is provided with a plurality of second metallized through holes, and the plurality of second metallized through holes are arranged in a rectangular shape; The third metal layer is provided with three through-matching grooves, the three matching grooves include two first matching grooves and one second matching groove; the second matching groove is provided between the two first matching grooves, and a metal strip is provided on the line connecting the midpoints of the two wide sides thereof; The third dielectric layer has the same structure as the second dielectric layer; A coupling window is provided at each end of the fourth metal layer, each coupling window is provided with a coupling patch whose size is smaller than the coupling window, and one end of the coupling patch is connected to the fourth metal layer; A differential feeding transition structure, a first band-pass filter and a second band-pass filter are provided on the metal feeding layer, the input of the differential feeding structure is connected to the external excitation structure, and the output is connected to the first band-pass filter and the second band-pass filter respectively; A plurality of pairs of radiation patches, a plurality of radiation slots, a plurality of pairs of first metallized through holes and a plurality of matching units are arranged correspondingly in the vertical direction, two coupling windows and two first rectangular slots are arranged correspondingly in the vertical direction, the first metal layer, the first dielectric layer and the second metal layer together constitute a leaky wave structure; the second metal layer, the second dielectric layer, the third metal layer and the third dielectric layer, the metal strip and the second metallized through hole together constitute a substrate-integrated coaxial line transmission structure.

2. A fixed-beam leaky-wave antenna with out-of-band filtering characteristics according to claim 1, characterized in that: The two ends of the rectangle in which the multiple second metallized through holes are arranged are located on the two long sides and the spacing between the second metallized through holes close to the wide sides is reduced to divide the space surrounded by the second metallized through holes into five parts, which are the first area, the second area, the third area, the fourth area and the fifth area, respectively, wherein the first area and the fifth area are located at the two ends.

3. The fixed-beam leaky-wave antenna with out-of-band filtering characteristics according to claim 1, characterized in that: The first area and the fifth rectangular area correspond to two coupling windows in a vertical direction respectively.

4. The fixed-beam leaky-wave antenna with out-of-band filtering characteristics according to claim 1, characterized in that: A plurality of radiation matching units are sequentially arranged on the metal strip along its length direction, and each radiation matching unit is composed of a metal patch.

5. A fixed-beam leaky-wave antenna with out-of-band filtering characteristics according to claim 4, characterized in that: The first radiation matching unit and the last radiation matching unit among the multiple radiation matching units are composed of two first metal patches, and the two metal patches are symmetrically arranged on both sides of the metal strip; the multiple radiation matching units between the first radiation matching unit and the last radiation matching unit are each composed of four first metal patches, every two first metal patches constitute a group, and the two groups of first metal patches are symmetrically arranged on both sides of the metal strip.

6. A fixed-beam leaky-wave antenna with out-of-band filtering characteristics according to claim 1, characterized in that: Each pair of radiation patches consists of two symmetrical rectangular metal patches, and both coupling windows are trapezoidal coupling windows.

7. The fixed-beam leaky-wave antenna with out-of-band filtering characteristics according to claim 1, characterized in that: The metal feeding layer is provided with a fourth rectangular groove, and two wide sides of the fourth rectangular groove are chamfered to form a trapezoidal structure similar to the coupling window.

8. The fixed-beam leaky-wave antenna with out-of-band filtering characteristics according to claim 1, characterized in that: The differential transition structure is prepared by CNC processing technology, and the substrate integrated coaxial line transmission structure and the leaky wave structure are both prepared by PCB substrate processing technology.

9. The fixed-beam leaky-wave antenna with out-of-band filtering characteristics according to claim 1, characterized in that: The radiation slots are bow-tie-shaped slots; and the matching slots provided on the third metal layer are all rectangular slots.

10. A fixed-beam leaky-wave antenna with out-of-band filtering characteristics according to any one of claims 1 to 9, characterized in that: A third metallized through hole is provided in the middle of the first area and the fifth area, and two pairs of fourth metallized through holes are provided at both ends of the third area respectively. The connection line of the two pairs of fourth metallized through holes is parallel to the connection line of the second metallized through holes forming the second area or the fourth area.

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